RJS5689 Posted December 30, 2009 Share Posted December 30, 2009 I have read the bellmouth vs divorced threads on here and don't know what to do. I am looking at some Megan and Invidia catless downpipes. The best deal I found was on an Invidia divorced downpipe (at agreat price shipped). I'm not sure what to do though. I have heard various things in different places some saying divorced is good and others saying it is bad. My plan for the car is to throw the downpipe in and go with a custom tune and be done with power mods for awhile. Will I see issues with the Invidia divorced downpipe that make going bellmouth better, or will it be too tough to notice a real difference? Link to comment Share on other sites More sharing options...
RJS5689 Posted December 30, 2009 Author Share Posted December 30, 2009 Well for what it's worth I just decided to order an Invidia divorced catless downpipe. Link to comment Share on other sites More sharing options...
Long Island Legacy Posted December 30, 2009 Share Posted December 30, 2009 lets put it this way, I had a Perrin divorced on my 07 lgt, 3" catless, and I still got tons of boost spikes and overboost, your going to get it either way. Link to comment Share on other sites More sharing options...
RIPjeep2002 Posted December 30, 2009 Share Posted December 30, 2009 With a proper tune, there is not much of a difference between between the two. Both sets are bellmouth, it is just that some DP's have a splitter to seperate the wastegate. I recently purchased an AVO DP with a custom 3in cat, and had to order a new bellmouth(previous owner had a twinscroll). The new one will be divorced, but I do not expect to loose hp over it. Link to comment Share on other sites More sharing options...
RJS5689 Posted December 30, 2009 Author Share Posted December 30, 2009 With a proper tune, there is not much of a difference between between the two. Both sets are bellmouth, it is just that some DP's have a splitter to seperate the wastegate. I recently purchased an AVO DP with a custom 3in cat, and had to order a new bellmouth(previous owner had a twinscroll). The new one will be divorced, but I do not expect to loose hp over it. That's exactly what I was thinking. I am planning on having an Infamous tune made for the car, but I am still aware that there could be boost creep/spike issues regardless of downpipe design. I just jumped on this deal because of the price I found it for. Excuse me for asking this rather "noob" is question, but this is my first Subaru. Why do we have boost spike/creep issues so frequently? Is it because of the mechanical wastegate? I had a GTI with the 2.0T FSI engine and it used an electronic blowoff valve and I never had boost creep/spike issues; neither did my friends with the same car. Or is it something related to our turbochargers, turbo design, etc. Link to comment Share on other sites More sharing options...
bama16 Posted December 31, 2009 Share Posted December 31, 2009 how a turbo builds boost with an internal gate....there is a rubber diaphram connected to a rod which controls the wastegate open and close. a boost controller controls the pressure on the diaphram therefore controlling the rod movement and wastegate movement. once desired boost is met the wastegate diphram will hold the wastegate flap at a certain spot so enough exhaust gas will pass the turbine to create boost, with the rest escaping through the wastegate and out the exhaust. if the wastegate is too small, then exhaust that is supposed to bypass the turbine doesn't , and in return creates undesired boost. Link to comment Share on other sites More sharing options...
subaggie Posted September 8, 2010 Share Posted September 8, 2010 Do you believe you'd still have the boost spike issue with the stock exhaust. I noticed the majority of peoples problems were with a catless downpipe and a high-flow aftermarket exhaust. I want to keep the rumbles down, so I was planning on doing a 3" catless dp with the stock exhaust. I also figured that with a little more backpressure from the stock exhuast that it would minimize the boost spiking. Any advice would be great! Link to comment Share on other sites More sharing options...
rao Posted September 8, 2010 Share Posted September 8, 2010 It doesn't matter - really. Rob IF YOU CARE ABOUT YOUR CAR YOU SHOULD NEVER DRIVE IT Link to comment Share on other sites More sharing options...
Dntk Posted September 9, 2010 Share Posted September 9, 2010 If you go with the Invidia make sure you grind down the divorcer some anyways, after reading up on it and seeing a lot of posts saying the problem with it was fixed i decided not to grind it down when i put it on my 09 LGT back in May, but ended up over boosting real bad and having to take it off and grind it down. Since I've ground it down I've had no over boost and running 17.5 psi on an Infamous1 tune. However i ground it down all the way so its basically just a bell-mouth now with a piece of metal in the middle Link to comment Share on other sites More sharing options...
subaggie Posted September 10, 2010 Share Posted September 10, 2010 Is yours with or w/o cats? Stock or aftermarket exhaust? Would you say that a tune is required with an aftermarket downpipe, or just a good idea? This is helping me a ton. Thanks. Link to comment Share on other sites More sharing options...
m sprank Posted September 12, 2010 Share Posted September 12, 2010 Welcome to the forum. This is the wrong thread for your question. It was dead until a few days ago, lol. There are LOTS of threads on stage2 and DP's. The short answer is NO, do not run a DP and no tune. Link to comment Share on other sites More sharing options...
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