Just recently installed SLP headers into the 92RS. I am currently waiting for my 3" in 3" out CATCO converter to replace my current catalytic converter. It will bolt to a 3" pipe going into the Borla exhaust. What adverse change will it have on the engine in regards to the new modification. The motor is stock other than the open-air element. Any help would greatly be appreciated.

 

Check the exhaust archives.There was a post about this same subject.The guy lost low end response.His motor was a stock 305tbi.He ended up going back to the muffler shop and they installed something(can't remember the name)in the intermediate pipe that restricted flow a tiny bit.This got back alot of the low end that he lost.I'm not sure but I thinkthey could just remove it later if he ever added mods and needed more flow.

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1987 Firebird Formula LG4,700R4,WS6,2.73 open rear
Current Mods:Flowmaster 3in. American Thunder cat-back,3in. Catco converter,L69 dual snorkel,K&N filter,roof console,Pioneer 1.5din cd player,BostonAccoustics 4x6plates,eclipse 6x9
ComingSoon! 350 crate motor(caprice),SLP coated 1 5/8 headers,edelbrock intake,edelbrock aluminum water pump

 

I have always heard that 3" exhaust is a bit much for a stock 305.

 

Thats what I always tell dudes here, some don't think so though. The same result every time, they put a 3in. on a stock 305 and they are looking for ways to get some Torque again.

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Looking For:

87 IROC-Z 350 TPI
84 TRANS AM 305 H.O.

 

LOL i must be an oddball, my stock 305 TBI just got modded (its first mod) with a Gutted high-flow cat and a Flowmaster american thunder 3" catback! no loss in low end, in fact i GAINED torque... yes this car is stock everything including paint lol... but it runs so much better now, honestly I dont beleive that backpressure crap anymore after this, im no genius but i do know when somthing makes the car run better, hell i even use less gas...

 

Well I kept my 2 1/2 in and 2 1/2 out cat but do have the 3" intermediate pipe on the car. (Just received my Catco 3"in and 3"out from Summit. Installation is on hold until I get my motor built.) As far as the current set up, car definitely feels different and especially at WOT. I put a block off plate on my Borla exhaust so that the exhaust flows straight to the muffler and took it out on I-5 so that. Cruising at 85 mph, I floored it and noticed an instant response. The 2 days that it took for me to install the SLP is well worth it.