2.5" vs 3" exhaust system
Thread Starter
Instructor
Joined: Jul 2008
Posts: 154
Likes: 0
From: CA
2.5" vs 3" exhaust system
Hello,
So here are several CA exhaust question
1.) Is a 3" Cat legal, since I've been calling a few places local to me (Fullerton/Chino Hills)... They all said they can't install a 3" Cat because its not legal, and I'm stuck with a 2.5" cat.
2.) What is the best configuration, 2.5" all the way from the headers? or 2.5" to the cat then 3" back out?
I really hate these CA smog laws, I've been researching this forum alot, which is why I've been asking a lot of questions and haven't done anything yet. Once again, thank you to everyone here for your help!
Car Specs
1978 L48 Auto Corvette (Everything Original)
Hedman Headers 68301 (waiting for it to be shipped)
So here are several CA exhaust question
1.) Is a 3" Cat legal, since I've been calling a few places local to me (Fullerton/Chino Hills)... They all said they can't install a 3" Cat because its not legal, and I'm stuck with a 2.5" cat.
2.) What is the best configuration, 2.5" all the way from the headers? or 2.5" to the cat then 3" back out?
I really hate these CA smog laws, I've been researching this forum alot, which is why I've been asking a lot of questions and haven't done anything yet. Once again, thank you to everyone here for your help!
Car Specs
1978 L48 Auto Corvette (Everything Original)
Hedman Headers 68301 (waiting for it to be shipped)
Thread Starter
Instructor
Joined: Jul 2008
Posts: 154
Likes: 0
From: CA
Hello,
The way its looking I'm probably going to have to do that as soon as my headers come in, Hopefully its money well invested since when I put the flowmasters in with the stock exhaust system, I didnt really hear a difference. My v6 mustang is louder than my vette.
The way its looking I'm probably going to have to do that as soon as my headers come in, Hopefully its money well invested since when I put the flowmasters in with the stock exhaust system, I didnt really hear a difference. My v6 mustang is louder than my vette.
Melting Slicks
Joined: Apr 2002
Posts: 2,337
Likes: 14
From: Norfolk VA
Do you have a dual exhaust set up? If I read your thread correctly it appears not. If you can in smogland, why not go with a dual exhaust system. As for sound you could have chambered sections welded in. Some say that chambered exhaust is restricting but there are no numbers to back this claim. You will like the exhaust note. Also IMO 3" pipes are overkill. 2.5" exhaust is suitable.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Your are dreaming! Corvette history 1978L = L48 350-cid V8, 175-hp
That is a NET rating from the factory. So you might actually have 200 ish back when it was brand new.
Summit racing sells a high flow 3 inch cat. I have friends that self installed them and they go unnoticed by the smog checkers because if it is installed in the stock location it is very hard to tell from the original. Also how many smog people have even done vettes?
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Thread Starter
Instructor
Joined: Jul 2008
Posts: 154
Likes: 0
From: CA
In due time, thats what I'm aiming for, as of right now for this summer I'm working on exhaust/suspension, then saving up for the winter to work on the engine comp cam260h, vortec heads, intake manifold etc.
Le Mans Master
Joined: Oct 2010
Posts: 6,938
Likes: 848
From: melbourne florida
2023 C3 of the Year Finalist - Modified
the converter. to a 84 era Monte Carlo SS had a great converter compared to what came on these cars and are 3" in and out I'd bet a smog station would pass it not knowing better, most of those clowns don't know what a carburetor looks like! if it were me, I'd move!