Exhaust opinion needed...

tydlwavs

Registered User
I've been reading since 5pm and I'm ready to ask my question.

I'm installing 95 exhaust manifolds in my 90 SC. I plan to port them at the outlet. I plan to order a set of the SCP downtubes. I am not sure if I'm getting them with or w/o cats.

My car is going to be mostly stock with maybe a 90 pulley installed. If I use a dual in 2.5" and single outlet 3" muffler in place of the resonator does anyone see an issue with a 3" to a 2.5" reducer right after the resonator? I plan to keep the stock muffler out back for now.

I'm going to fish around for some resonator part numbers now:)

Thanks,
Todd
 
i dont see a problem with that.

thats actually how i have my exhaust now ; ported manifolds, 2.25" catless downtubes, 2.5" dual in/3" single out magnaflow resonator and reduced to 2.5" around the tank and out back.

whenever i find a later gas tank i'll have the 3" pipe thru the tank installed
 
Do you have a video clip of that car w/o the cats. That is the only thing I need to determine.

I'm doing this as described for the same reason. I can add 3" catback later.
 
Todd, why the 94-95 exhaust manifolds? I didnt think you had to pass emissions where your at so I would ditch the cats. Im leaving my exhaust alone untill its on the road and after the final emissions test the cats are gone. They will give you louder exhaust note but I think the muffler idea insted of the resonator should work out great. Let us know what part # works. I have a 95 tank and new pump and flomaster cat back I took of a car I junked so all I will need is a resonator or muffler and some down tubes for this buget SC. Oh and a bag of cash:rolleyes:
 
Todd,here is my set up when I had it on the car :stock ported manifolds,2.25" down-tubes with 2.5" high flow cats,dual 2.5'' into single 3'' and back to dual 2.5", dynomax muffler in place of resonator,no mufflers in the back.It was kind of quiet at idle and pretty loud at wot.Video

Derek
 
Mark, Being an Environmental Health employee I have seen the light and I prefer to keep the cats unless cost really comes into play. I am installing a complete 95 motor and the manifolds came with the engine. I read a couple posts about the pass side on the 94/95 being a better options so I am going that route.

I have not had to test on the rollers with my 05 and I won't with the 90. I am just trying to make a decision on the downtubes.

Derek, I have listened to your car and I'm not sure if I'll like it that loud. I would like to keep the stock mufflers out back with the stock 2 1/4 pipes.
 
Mark, I am installing a complete 95 motor and the manifolds came with the engine. I read a couple posts about the pass side on the 94/95 being a better options so I am going that route.

I have not had to test with my 05 and I won't with the 90. I am just trying to make a decision on the downtubes.

Derek, I have listened to your car and I'm not sure if I'll like it that loud. I would like to keep the stock mufflers out back with the stock 2 1/4 pipes.
 
(Mark, Being an Environmental Health employee I have seen the light)

I could not agree with you more but for a car that will see less than 1000 miles a year as this will be my toy. I forgot you were useing a 95 motor, that expains it. I too like to keep it quiet. I like the blower whine better than the exhaust note. Summit sells high flow cats cheap and can be welded into the down tubes.
 
Nowadays from the tests and everything I've read about, using hi flow cats causes very little restiction and is not a problem for 95% of us in the club. Its the real hi po guys that may feel it, but by that time most of those cars are not really getting street driven anyway.

The cats will also help with the sound, and could help get rid of the drone. I'm running stock cats, no resonator and the older style split and stock mufflers at the rear (even though I've got the newer tank installed.. a little welding goes along way ;) ) and I don't get any drone and the car is not loud.
 
emissions

I've got a 95 SC and would like to upgrade exhaust but want to keep the smog nazis here in CA happy. I am thinking of getting the 2.5" downtubes that bolt up to the stock manifolds with high flow cats from SCP.Then I was gonna go with Flowmaster resonator with Flowmaster true dual 2.5" to the rear with there mufflers.

Does this sound like I should be *cool* with CA emissions?
 
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