Masshole Posted August 6, 2011 Share Posted August 6, 2011 I had purchased an OEM downpipe with both cats gutted, but I'm having some second thoughts before installing. I recognize that this may wind up leading to some headaches in terms of state inspection and whatnot. How worthwhile will the pipe actually be, in terms of exhaust flow, power gains, fuel economy, or any combination thereof? The car is currently tuned, and would be retuned after installation if I move forward. Any thoughts? Link to comment Share on other sites More sharing options...
compsurge Posted August 6, 2011 Share Posted August 6, 2011 Stink, CEL without a tune to remove it. You would need a stage 2 tune. Since you are an '05, you probably need to replace with the uppipe with a catless unit. With stage 2 tune, you should notice quite a bit of power increase Link to comment Share on other sites More sharing options...
Max Capacity Posted August 6, 2011 Share Posted August 6, 2011 I would think as long as it's tuned and programed correctly there should be on way to tell the cats are empty. It's not like they take the pipe off and look inside. 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
Masshole Posted August 6, 2011 Author Share Posted August 6, 2011 I've got the catless up-pipe and there's no question about whether or not I want to install that. My big concern was whether the cat removal in the DP would be worthwhile. Sounds like it will be Link to comment Share on other sites More sharing options...
fahr_side Posted August 6, 2011 Share Posted August 6, 2011 You will get about the same power as with a catted aftermarket item but it will spool later, your boost control will be less accurate and the exhaust will stink. Having tried both, I'd run the aftermarket part and swap the stocker for inspections. Obligatory '[URL="http://legacygt.com/forums/showthread.php/2008-gh8-238668.html?t=238668"]build thread[/URL]' Increased capacity to 2.7 liters, still turbo, but no longer need spark plugs. Link to comment Share on other sites More sharing options...
ShatzGT2 Posted August 6, 2011 Share Posted August 6, 2011 Am I the only crazy one that actually likes the smell of the exhaust after going to a cat less 3'' DP ?? ....all environmental issues aside, something about burnt gasoline and rubber throws me back the days of driving my dads 70' 454 Chevelle at 14yrs old hahah Link to comment Share on other sites More sharing options...
LosAngelesLGT Posted August 6, 2011 Share Posted August 6, 2011 Yes, you are the one. Don't feel bad. So was Neo in the Matrix. I'd run a race catted open bellmouth DP loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong before I would run a de-catted oem pipe. Either way you are greasing palms to get though smog. May as well run without stink and have more power throughout the rpm range. Link to comment Share on other sites More sharing options...
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