whitetiger Posted June 6, 2006 Share Posted June 6, 2006 Couldnt really find a straight answer. The reason i ask is that im going to install a qtec electric cut-out and i want to put it before the resonator, but ther is very little room for it there. Is the resonator a "straight through" construction surounded by baffling, or does it restrict exhaust flow. My goal is to have a stock sounding exhaust when the qtec is closed and to have it ultra loud and free flowing when the qtec is open. Link to comment Share on other sites More sharing options...
PhilT Posted June 6, 2006 Share Posted June 6, 2006 The resonator is straight through, doesn't restrict at all, just deadens the sound. Double Award Winning Legacy GT Wagon Link to comment Share on other sites More sharing options...
whitetiger Posted June 6, 2006 Author Share Posted June 6, 2006 ok good. then I can put the cutout behind it where there is alot more room on the pipe to play with. Link to comment Share on other sites More sharing options...
Xenonk Posted June 6, 2006 Share Posted June 6, 2006 You have room under there.. best to put the cutout at the end of the downpipe.. Keefe Link to comment Share on other sites More sharing options...
whitetiger Posted June 6, 2006 Author Share Posted June 6, 2006 You have room under there.. best to put the cutout at the end of the downpipe.. we are talking aout the the exhaust, right? The Y-pipe is restrictive. I was just curious about any restriction before the that, where id have the put the cutout in front of. oops, misread your post. i know there is room, but not alot. if the resonator is not restrictive, i can put it after it to make the install alot easier. Link to comment Share on other sites More sharing options...
mccorry Posted June 6, 2006 Share Posted June 6, 2006 The Y-pipe is restrictive? It doesn't look restrictive to me.... Link to comment Share on other sites More sharing options...
bladerunner Posted June 6, 2006 Share Posted June 6, 2006 I believe the 3rd cat (midpipe) is your last big restriction, especially for protunes. Link to comment Share on other sites More sharing options...
NHLEG Posted June 6, 2006 Share Posted June 6, 2006 Depends who you talk to about the Y-pipe. It is definately more restrictive than an aftermarket Y-pipe/catback with a larger diameter pipe and good, smooth Y design. Â My personal experience is that my SP2 helped alot over the stock Y-pipe. Peter's car (PLtek) had almost the same mods as my car except he had the stock Y and center pipe with aftermarket cans (AVO) and on the same dyno (XXTuning) with the same tuner (Tony), my car made 20 more HP and 10 less lb/ft with 1 lb less boost (Tony could have pushed more out of it, but I was happy w/ 270/325:) ) and a much flatter torque curve. It was his belief that the catback was the difference between the cars. Link to comment Share on other sites More sharing options...
whitetiger Posted June 6, 2006 Author Share Posted June 6, 2006 Depends who you talk to about the Y-pipe. It is definately more restrictive than an aftermarket Y-pipe/catback with a larger diameter pipe and good, smooth Y design.  My personal experience is that my SP2 helped alot over the stock Y-pipe. Peter's car (PLtek) had almost the same mods as my car except he had the stock Y and center pipe with aftermarket cans (AVO) and on the same dyno (XXTuning) with the same tuner (Tony), my car made 20 more HP and 10 less lb/ft with 1 lb less boost (Tony could have pushed more out of it, but I was happy w/ 270/325:) ) and a much flatter torque curve. It was his belief that the catback was the difference between the cars. That is what I suspect. the Y-pipe is the most restrictive part of the stock Cat-back. So bypassing that with the cutout is my main concern. Now i know id ont have to worry about the resonator, i can put the cutout after it. Link to comment Share on other sites More sharing options...
LIZARD Posted June 6, 2006 Share Posted June 6, 2006 actually, the stock cans are prob. more restrictive than the Y-pipe. Stage2.5376, TDC ProTune,blah blah blahhhh and....Alky/H20 injection Link to comment Share on other sites More sharing options...
Guest *Jedimaster* Posted June 6, 2006 Share Posted June 6, 2006 The Y-pipe is restrictive? It doesn't look restrictive to me.... Link to comment Share on other sites More sharing options...
TRS Posted June 6, 2006 Share Posted June 6, 2006 jBy just by peering down into my removed resonator, it looks to be a perforated straight through pipe designed to cancel out unwanted (per Subaru engineers) exhaust frequencies. I don't think it's very restrictive. The stock Y is crimped or flattened somewhat to provide clearance between the exhaust, ground and undercarriage components and does look to be a pinched-off and a bit restrictive.  The OEM mufflers are good at limiting the exhaust tone and volume but may not actually be that restrictive. Link to comment Share on other sites More sharing options...
Xenonk Posted June 7, 2006 Share Posted June 7, 2006 we are talking aout the the exhaust, right? The Y-pipe is restrictive. I was just curious about any restriction before the that, where id have the put the cutout in front of. yes, I said to put the cut out before the 3rd and final cat (and you can get a catless downpipe as well, but just watch for boost creep as STi owners noticed this as well and left the catted downpipe in place).. my previous intention was to install a shorty-downpipe and put the cutout between the downpipe and the stock cat.. the cats themselves are restrictive already as it's their JOB to soak up all the heat that gets pass through.. to make a cat effective, there's a lot of layers of mesh and chambers that slows down the exhaust flow so that it can soak up the heat, afterall, the cat is using heat as the catalyst (duh) to make sure that everything is burning up and converting to CO to C02s, etc etc.. it needs heat to do this and to make stoichiometric point of 14.7:1 the Y-pipe is where the resriction stops as the two 2.125" I.D. pipes have already more flow than a single 2.5" I.D. pipe. If anything, the restriction starts at the downpipe (from a 3" piping and narrows down to a 2.5" or smaller I.D. piping..  You will see a series of different designs for downpipes that cater to internal wastegate turbos.. two common ones are divorce pipes which help ease out the exhuast flow by creating a directed pipe for the wastegate to dump into a seperate pipe that is later either join back into the main part of the down pipe or that it just dumps out by itself.. the other is the bell-mouth type that basically has a huge opening that allows both the waste gate side and the main exhaust side to just flow out and into the downpipe in a smoother fashion. Stock Flange: http://www.vwrx.com/images/down-pipe-flange.jpg http://www.oakos.com/Merchant2/graphics/00000001/OADP_02.jpg Bell-mouth: http://www.hotsubarus.com/ProductImages/cobb/cobb%20downpipe.jpg Divorce: http://www.crucialracing.com/images/dp2_300.jpg  A good reason why downpipes on even stock ECU'd cars are beneficial: http://img360.imageshack.us/img360/108/downpipecomparo4cu.jpg  Swap out the downpipe for a shorty type, use the cutout as your "bridge" from the shorty downpipe to the stock cat and you'll be golden.. I would have done it this way a long time ago, but due to my class rules and some track rules, I can't do such things. btw, if anyone wants to make their own exhaust, here are all the flanges you need.. http://www.vwrx.com/index.php?pg=flanges  that downpipe flange is your biggest problem when it comes to making power for ANY bolt-on TD06 turbo.. Keefe Link to comment Share on other sites More sharing options...
BDII Posted June 7, 2006 Share Posted June 7, 2006 Nice write up Keefe! thanks! Need forum help? Private Message legGTLT Link to comment Share on other sites More sharing options...
whitetiger Posted June 7, 2006 Author Share Posted June 7, 2006 I already have a Cobb catless DP (been stage 2 for about a year now)which i dont want to modify, so im just worrying about the stock catback i still have. still good for the newbs to know. Link to comment Share on other sites More sharing options...
Xenonk Posted June 7, 2006 Share Posted June 7, 2006 just move the stock cat back.. you want the cut-out before the cat.. that's where you will gain the most.. Keefe Link to comment Share on other sites More sharing options...
whitetiger Posted June 7, 2006 Author Share Posted June 7, 2006 just move the stock cat back.. you want the cut-out before the cat.. that's where you will gain the most.. I dont have a stock cat. (cobb catless DP and Maddad headers w/ catless UP). I just was wondering if the resonator was restrictive enough to go though the hassle of trying to put the cutout in the little space in front of the resonator. The answer is its not restrictive so i can put it behid the resonator before the y-split. i misread your first post btw Link to comment Share on other sites More sharing options...
Xenonk Posted June 7, 2006 Share Posted June 7, 2006 where's your 3rd cat?? there's one more cat of where the last o2 bung is attached to.. the resonator is located AFTER your 2nd o2 sensor.. Keefe Link to comment Share on other sites More sharing options...
whitetiger Posted June 7, 2006 Author Share Posted June 7, 2006 no, there is one on the UP which is gone, then 2 on the DP/mid pipe which is gone due to my full length catless DP. I originally wanted to put the cutout rigth ater the DP to Center pipe flange(the one with the graphite donut gasket and spring loaded bolts to avoid cutting up my nice cobb DP, but there is very little room between that flange and the resonator. Alot more pipe to play with after the resonator, before the y-split. Â Â heres a pic of what i mean. i originally wanted to put the cutout where the red arrow points in order to bypass a potentially restrictive resonator, but since its not, ill put it where the blu arrow points sice the is alot more space. Link to comment Share on other sites More sharing options...
TSiWRX Posted June 7, 2006 Share Posted June 7, 2006 Just be sure you've got a good plan to take care of the rear O2 CEL(s) if you do the pre-third-cat (which would, IMveryHO, definitely be the way to go!) bypass.  As for "restriction?" I'm of the opinion that, at this particular time, who the hell really knows!  There's been more than one very respected tuner/Vendor here who has identified differing components (post third-cat section) as the one(s) that cause the bigger restriction. Depending on who you take after, this could be either the Y or the cans, and the data they provide will prove their individual case very well. My take? Just do the entire thing! Covers all angles! <-- I love Winky, my "periwinkle" (ABP) LGT! - Allen / Usual Suspect "DumboRAT" / One of the Three Stooges '16 Outback, '16 WRX, 7th Subaru Family Link to comment Share on other sites More sharing options...
Xenonk Posted June 7, 2006 Share Posted June 7, 2006 no, there is one on the UP which is gone, then 2 on the DP/mid pipe which is gone due to my full length catless DP. ah, that's why.. I thought you had a shorty dp.. I would actually hack up the downpipe to put the cutout there.. that way, you can keep your resonator in place to keep things quiet.. what you could do is just hack out the stock resonator out of that pipe and put on an aftermarket shorter one like a Vibrant version. Keefe Link to comment Share on other sites More sharing options...
hal9e3 Posted June 7, 2006 Share Posted June 7, 2006 At what point should I consider upgrading the header? I'm assuming it should wait until after DP (done), UP (TBD), filter (done) and T/CBE (soon). Is it a worthwhile investment on its own, is a turbo required to make it worthwhile or should I just skip it and start thinking about just upgrading the turbo? Crap, this was supposed to be a new topic. Moderator, please move or delete. Link to comment Share on other sites More sharing options...
Xenonk Posted June 7, 2006 Share Posted June 7, 2006 you can take out the stock header for something a little bit less restricting.. when you start hitting anything north of 500whp, you might want to get something like an equal length header (and lose the boxer sound) to keep the pulses equally spaced.. you then will see a gain at the higher end as your turbo is now spinning at a smoother rate than in surges. Keefe Link to comment Share on other sites More sharing options...
derffred Posted June 11, 2006 Share Posted June 11, 2006 how much louder will it be without the resonator but the stock cans... let's say i cut out the resonator an welded in a straight pipe... Link to comment Share on other sites More sharing options...
Xenonk Posted June 12, 2006 Share Posted June 12, 2006 few people done this.. you just get more of a boxer rumble than anything.. I had a few people that left the stock resonator and replaced the mufflers with straight pipes instead (a la SRT4 style) and it's not as loud as you think.. even my car I replaced the entire catback section with just a 2.5" straight pipe that terminates at the end of the rear axle and it's fairly simple and not as loud as it can be.. the cats acts as resonators anyways.. I have a few videos of my car in the video with a the straight pipe on and it's just fine.. cops dont care either cuz it's not loud at all.. besides, cops are too busy looking for large mufflers and huge cans, well, I dont have any Keefe Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.