GTTuner Posted August 21, 2006 Share Posted August 21, 2006 I have read many members here actually "gutting" the OE down pipe. Is there any downside to this vs purchasing a pipe without a cat? Seems like the OE pipe gutted would have a rather large "chamber" where the cat used to live. Does it make the exhaust sound crappy? Not so much sound out the back, but sound up near the engine. I ask because I have gutted cat's on other cars before, and the exhaust has a strange tone after. Input would be apprecieated. I have gaskets in hand as we speak:icon_bigg Link to comment Share on other sites More sharing options...
SpeedNeeder Posted August 22, 2006 Share Posted August 22, 2006 I think you will get CEL's without a.... OIC u have one of those AP things already. My other car is a 1993 Chevy S-10 Tahoe! (Currently being driven to failure by my nephew) Link to comment Share on other sites More sharing options...
mbacis Posted August 22, 2006 Share Posted August 22, 2006 Haven't heard people complain about the sound with a gutted DP. There is some power to be gained from swapping it out, as the stocker is not open to the area where the wastegate dumps, the gases are blocked and forced to work their way out with the gases passing through the turbine. I can let you know after this weekend how it sounds, but it sounds like you'll be doing it before then. In that case, let me know. Link to comment Share on other sites More sharing options...
Waxiboy Posted August 22, 2006 Share Posted August 22, 2006 I think the DP to turbo configuration (bellmouth/divorced) will be more beneficial than going catless. Link to comment Share on other sites More sharing options...
HansGT Posted August 22, 2006 Share Posted August 22, 2006 I think you will get CEL's without a.... OIC u have one of those AP things already. nope....I think your thinking the sensor in the up pipe? if your gutting you can get by with just doing the cat in the first section of the downpipe as its the most restrictive. You can leave the cat in the mid section of the downpipe and keep things more quite and still run a stage 2 map. I've asked TDC and they recommend going aftermarket with the downpipe either shorty or full. The stocker, I believe, has an odd plate or something that could disrupt flow where an aftermarket would not. Link to comment Share on other sites More sharing options...
rabydanimal Posted August 22, 2006 Share Posted August 22, 2006 I just installed a gutted stock DP this weekend. I'm sure going aftermarket will gain a few extra HP if you reflash with the AP but a gutted stocker is probably 95% there. It does have a blank plate on the turbo side whereas most aftermarket DPs have some sort of opening there be it divorced or a bellmouth. Yes it makes a difference, but not to your butt. You can't beat the price and Subaru is none the wiser when you have the car in for service. I didn't notice much change in sound since I'm already running with a Magnafow catback exhaust. Using the gutted stocker will be the same sound you get from any aftermarket pipe. There's nothing you can do to make the Legacy's exhaust sound bad. Just look at Hogmeat's Hogzaust system, yikes. Link to comment Share on other sites More sharing options...
Spinjockey Posted August 22, 2006 Share Posted August 22, 2006 ^^^ Why would the blank plate reduce power? It just covers the wastegate, so I could see problems with boost creep (which there's been no reported cases of), but not problems with power. Link to comment Share on other sites More sharing options...
HansGT Posted August 22, 2006 Share Posted August 22, 2006 ^^^ Why would the blank plate reduce power? It just covers the wastegate, so I could see problems with boost creep (which there's been no reported cases of), but not problems with power. increased boost creep as you mod. the further you go away from stock the more of an issue. Link to comment Share on other sites More sharing options...
SpeedNeeder Posted August 23, 2006 Share Posted August 23, 2006 If you have access to an end mill, could you not correct the plate problem in front of the WG? Or is there more to it? I don't know, I've never had my down pipe off. I thought gutting the second and third cats gave a CEL on the rear O2 sensor? Of course, I really have no idea what I'm talking about, so I very well could be wrong. My other car is a 1993 Chevy S-10 Tahoe! (Currently being driven to failure by my nephew) Link to comment Share on other sites More sharing options...
racerdave Posted August 23, 2006 Share Posted August 23, 2006 I just installed a gutted stock DP this weekend. I'm sure going aftermarket will gain a few extra HP if you reflash with the AP but a gutted stocker is probably 95% there. It does have a blank plate on the turbo side whereas most aftermarket DPs have some sort of opening there be it divorced or a bellmouth. Yes it makes a difference, but not to your butt. You can't beat the price and Subaru is none the wiser when you have the car in for service. I didn't notice much change in sound since I'm already running with a Magnafow catback exhaust. Using the gutted stocker will be the same sound you get from any aftermarket pipe. There's nothing you can do to make the Legacy's exhaust sound bad. Just look at Hogmeat's Hogzaust system, yikes. What O2 cel fix did you use? Is it working? Link to comment Share on other sites More sharing options...
rabydanimal Posted August 23, 2006 Share Posted August 23, 2006 No need for a cel fix when you have the AP. It suppresses any codes thrown by the exhaust sensors. If you have access to an end mill, could you not correct the plate problem in front of the WG? Or is there more to it? I don't know, I've never had my down pipe off. You can't machine out the blank plate as you would cut right through the plate and have yourself a major hole in your exhaust. Check out Jedi's DP install thread. Pic from that thread below: http://premium1.uploadit.org/cultofthejedi//crucialdownpipe007.jpg Original thread: http://legacygt.com/forums/showthread.php?t=16889 Link to comment Share on other sites More sharing options...
SpeedNeeder Posted August 23, 2006 Share Posted August 23, 2006 I just installed a gutted stock DP this weekend. I'm sure going aftermarket will gain a few extra HP if you reflash with the AP but a gutted stocker is probably 95% there. It does have a blank plate on the turbo side whereas most aftermarket DPs have some sort of opening there be it divorced or a bellmouth. Yes it makes a difference, but not to your butt. You can't beat the price and Subaru is none the wiser when you have the car in for service. I didn't notice much change in sound since I'm already running with a Magnafow catback exhaust. Using the gutted stocker will be the same sound you get from any aftermarket pipe. There's nothing you can do to make the Legacy's exhaust sound bad. Just look at Hogmeat's Hogzaust system, yikes. I would guess a gutted stock pipe would be quieter because it is cast and has a heat shield as opposed to 3rd party tubing and no heat shield? My other car is a 1993 Chevy S-10 Tahoe! (Currently being driven to failure by my nephew) Link to comment Share on other sites More sharing options...
SpeedNeeder Posted August 23, 2006 Share Posted August 23, 2006 No need for a cel fix when you have the AP. It suppresses any codes thrown by the exhaust sensors. You can't machine out the blank plate as you would cut right through the plate and have yourself a major hole in your exhaust. Check out Jedi's DP install thread. Pic from that thread below: Original thread: http://legacygt.com/forums/showthread.php?t=16889 Wow, great pic, now I understand. I agree that it's not ideal, but I would guess you get ~80% of the gains with the gutted stocker. My other car is a 1993 Chevy S-10 Tahoe! (Currently being driven to failure by my nephew) Link to comment Share on other sites More sharing options...
GTTuner Posted August 24, 2006 Author Share Posted August 24, 2006 Thanks for all your input guys. So a stocker gutted would be probably 85% of the gain I might get with an aftermarket pipe? Also, you mention the second cat (or third). That is the one on the mid-pipe under the car????? Link to comment Share on other sites More sharing options...
rabydanimal Posted August 24, 2006 Share Posted August 24, 2006 Yes and yes Link to comment Share on other sites More sharing options...
GTTuner Posted August 24, 2006 Author Share Posted August 24, 2006 Yes and yes Before you said it wasn't something you feel in the "butt dyno". I won't even bother if you can't feel a difference. Did you do other mods also? Link to comment Share on other sites More sharing options...
rabydanimal Posted August 24, 2006 Share Posted August 24, 2006 My only other mod is a cat-back 2.5" exhaust. I can't say from personal experience that I can't feel the difference since I haven't had both types on my car but I believe there are datalogs on this forum that prove gutted DPs are very similar to aftermarket pipes. Link to comment Share on other sites More sharing options...
SpeedNeeder Posted August 25, 2006 Share Posted August 25, 2006 A lot of mods are hard to detect with the butt dyno, however, the other car dyno is generally pretty accurate! My other car is a 1993 Chevy S-10 Tahoe! (Currently being driven to failure by my nephew) Link to comment Share on other sites More sharing options...
GTTuner Posted August 25, 2006 Author Share Posted August 25, 2006 ^^^^ True, sometimes it's not an actual increase in power, just more power in different areas of the RPM range. Same with my rice rocket, I added a complete header and exhaust, plus jetted the carbs. My peak HP only increased 3 ponies, but I have torque out the rear end from 6k to 10.5k rpm that I didn't feel before. I'm hoping with the DP gutted and a UP, then flashing stage 2 I should notice a difference. "Gaskets in hand, have hammer and chisel, will travel":icon_bigg Link to comment Share on other sites More sharing options...
Waxiboy Posted August 25, 2006 Share Posted August 25, 2006 Why not just get a shorty DP then gut the 3rd cat. Link to comment Share on other sites More sharing options...
GTTuner Posted August 25, 2006 Author Share Posted August 25, 2006 ^^^^^ Love to but $$$$ is tight right now. Link to comment Share on other sites More sharing options...
hogmeat Posted August 25, 2006 Share Posted August 25, 2006 just gut it! i have gutted all my pipes and am catless - definately noticed a throttle response difference RIGHT away, in addition to quicker spool up and a top-end that just doesn't drop off!!! I don't know if there was added "HP", but quicker spool, better response, and better top end all make it well worth while!! Then, after going 2 weeks like that, I added a AP and TDC Stage 1 - and yeeeha! I'm pleasantly surprised... It was most certainly worth the couple bucks and 10 mins of my time. CLICK HERE FOR THE HOGZAUST Link to comment Share on other sites More sharing options...
rabydanimal Posted August 25, 2006 Share Posted August 25, 2006 Hell yeah. I wish I had the time to do my U/P. Rock on and good luck passing emissions. Link to comment Share on other sites More sharing options...
hogmeat Posted August 26, 2006 Share Posted August 26, 2006 Hell yeah. I wish I had the time to do my U/P. Rock on and good luck passing emissions. iowa = corn = which also = no emissions! I'm pleasantly surprised... It was most certainly worth the couple bucks and 10 mins of my time. CLICK HERE FOR THE HOGZAUST Link to comment Share on other sites More sharing options...
GTTuner Posted August 28, 2006 Author Share Posted August 28, 2006 Did the DP Friday night. The two top bolts holding the flange to the turbo were missing the nuts. Only the heat shield was stopping them from falling out!!! Amazingly it didn't leak. Anyway, I flashed stage 2 and did a couple of runs.....holy crap!!!! I pulled off the highway and when I turned and punched it in first the whole car broke loose and spun all 4 wheels sideways. The road was damp, but I NEVER experienced that kind of power in this car. It pulls 5k to 6500 VERY hard. I'm very impressed. So I went back to me TDC stage 1 for now until I order my new UP from TDC "just in case" it's hurting it. Damn.....loving it. Link to comment Share on other sites More sharing options...
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