: 3" Exhaust all the way back?

05-27-09, 11:15 PM
I have a 95 STS that is going to need some exhaust work done due to leaks at the Y pipe. I have read thread after thread on optimum set up. Seems to be 3" from cat to Y then 2 1/5 into muffler (brand of your choice). Why not just a 3" sewer pipe all the way back to a single 3" muffler then single or dual outs at the rear? Is anything gained by keeping the Y pipe? I would like to just do the 1 muffler and go with a center exit / twin tip exhaust right up the middle and add a second cutout to the bumper cover. Both for cost savings and uniqueness. Any thoughts?

05-28-09, 09:40 AM
Quite a bit of work for no gain, but no reason not to if you know a GOOD mandrel bend shop.

Don't get too creative because there have been some problems with emissions and engine codes setting due to changes in the exhaust flow which trip a catalytic convertor efficiency SES light.

The pipe to the cat and from the cat is about 2 1/2" and the Y and outlets vary from 1 5/8" to 2" because of the way the benders crimp the bends.

For my .02, duplicate the setup in 3" to a 2 1/2" Y with a good set of s/s mufflers and CORSA tips. www.corsaperformance.com

05-28-09, 03:28 PM
Single exhaust seems like it would be an easier set up since I would not have to have the shop put in a y pipe. They would just duplicate the stock pipe just with a larger size. The stock y pipe is right at the rear wheels, where it would be just as easy to intall a single can there. A place near me quoted me $170 with a 40 series Flowmaster complete. I was looking at some of the manufactures web sites and it seems that I would not loose very much with one muffler flowing 3" exhaust vs. 2 mufflers flowing 2 1/2"

Are the error codes from a too free flowing exhaust a problem in OBDI cars or just the newer ones?

05-28-09, 09:14 PM
obd-1 should not have an issue with the cat conv. codes since they dont have a o2 after the cat.

I would say you are in the clear for that.