I have been researching the boards and it appears that everyone says don't go any smaller than a 3" cat back exhaust system. But I haven't seen anyone explain why. So I was wondering what are the benefits for going with a 3" exhaust system vs a 2-1/2"? I just bought a 92 Camaro RS with a 305 TBI about a month ago and would like to replace the stock exhaust, so an explanation of why 3" over 2-1/2" would be appreciated. Thanks!

And recommendations for systems would also be appreciated.

 

go with true duals all i got to say. i bought my car (same as yours) took the 2 1/4 cat back off and put a 2 1/2 on made no differance in the performance but waht do you expect with the stock headers and y-pipe then i smartened up and just put true duals on so dont bother with the 2 1/2 its a waste of money/ time

 

basically its more airflow through a 3" but to big and it hurts the performance not enough back pressure. whatever you do dont go flowmaster, personally im curious about the gmmg chambered exhaust but at its price it would take a hard and long decsion.

 

back pressure is never a good thing, on a TBI the bottlenecks will be the manifolds, not the catback, so you might as well just get the 3" to give you room to grow later on.

 

jason1313, for the correct explanation you need to read the "all about backpressure" stiky on the top of this forum.

I personally read it but dit not understand wery much more than that 3" was the size these 305 tbi cars need to run with all the emission friendly accessories.

I have #TF8692 MAC headers 2x2.5" to 3" collector, #CTO9118 catco 3" highflow cat and #HOK16823 hooker 3" cat back with 2x2.5" dinomax exhaust pipes(because I dont like the included pipes from hooker) .

It made a nice difference from the embarrassing stock power and no problems or anything other then the stupid exhaust noise from 2000rpm up. The car runs like perfectly.

 

Thanks for all the replys!

After reading your replys and researching abit more. I have decided to go ahead and go with a 3" system. What do you all think of these for my 92 RS 5.0 TBI?

http://store.summitracing.com/partde...186+4294903638+

 

If your doing only the cat back I would keep the stock one if its not falling appart because power will be the same.
Or use the #hok 16823 including the 3" highflow cat. So you will be ready for the day you put the headers.
Edelbrock has also a little less expensive ones with nicer tail pipes.

 

The Cat-Back is just what i am starting with, I am planning on replacing the rest of the exhaust when I can. Whats the differnence between the HOK-16823 and the HOK-16820? From what the Summit Racing applications site says the HOK-16823 won't work for my tbi 305 VIN E. Is there actually a difference or the Summit Racing site just saying that?

http://store.summitracing.com/partde...&view=32&N=700+

http://store.summitracing.com/partde...186+4294903638

 

I have the Flowmaster CatBack With MagnaFlow highflow cat 3" System and mine is good! I like it nice rumble and slight increase inpower...It say go with the same set up...Like you im going to eventually change the headers and y pipe on mine because they are so damn restrictave but IDK about messing with the whole air thing on the headers so im intimidated also I have a 89 RS 305 VIN E TBI so we have the same car just 2 years apart

 

Jason1313, loock at the intermedite pipe were it goes connected to the cat converter. 16820 has a reducer to fit the stock cat. 16823 ist for 3" cat converter.
If you add a 3"cat converter to your investment you can buy a 15$ slip fit reducer to weld to your y pipe and just slip it of wen you add headers. I hope this clears things up.

 

Yes it does. Thanks, Thomas!

And thanks to everyone else as well, everyone is very helpful!