[Buick Runner]

The exhaust in my Regal is rusted out so I will be replacing most of it, would it be worth it to increase it from the stock 2 dia pipe to a 2 1/2 pipe dia for a N/A V6? or would there not be much of an improvement?

 

[tony moore]

a good muffler will help much more than bigger pipe. but 2 1/2 looks cool! at some muffler shops its the same price or close to it!!

 

[Buick Runner]

Thanks tony.

 

[Freddie's Regal]

2-1/2 is way too big....

Max should be left at 2" if you're going with an OEM system. I have a true duel exhaust with H-pipe and Pace-setter headers along with Flowmasters. With this arrangement I stepped up to 2-1/4". I have no doubts this was a major improvement in HP.......(for an N/A).

I personally think that a slightly beefy N/A can really rock with a good cat, (if your state mandates it), and any of the three G-Body 'Y' pipe and tail system, (Cutlass 442, Monte Carlo SS, Buick GN will work). The two best mufflers for this combination would be Dynomax or Hooker.

 

[tony moore]

so 2 1/2 is way to big but you have 2 1/4 on your car? :dunno:

 

[Freddie's Regal]

The stock 'Y' pipe versions are all 2-1/4". I've seen after-market ones offered up to 2-1/2". I'm not sure that opening the V-6 N/A up to that kind of flow is all that necessary unless you're more inclined to do track times instead of daily driving. And even then I don't think there is much benefit. :yup:

Unlike the turbo versions that are naturally restricted due to the turbo, the N/A V-6 needs a little restriction. Overall I think my system is much better than the stock non-'Y' pipe type, but over-kill. The system I mentioned above would be excellant for the V-6 N/A, and probably more practical then the one I currently have. :sw:

 

[b4black]

I think the stock exhaust manifolds are the restriction.


I'd find a set of 79/80 manifolds.

 

[Buick Runner]

In my state you need a cat to pass the tests, so I am thinking about a high flow cat. I am not sure what you mean by a y pipe, in my car it has the stock manifolds with a crossover pipe going from the diver side manifold to the pass side manifold, then another pipe comes out of the pass side manifold to the cat then out and makes a catback over the rear axle (this is were it is rusted out on the pipe) to the muffler and then out. it is not a very good exhaust system. I am going to keep the stock manifolds since the headers I have seen for Buick V6s do not have the smog hookups and the crossmemeber in my frame has only one hump they do sell double hump one but they cost too much and too much work to put in.

 

[Freddie's Regal]

The N/A Buick is a 'G'-body style. Some other G-Body styles are Pontiac Gran Prix, Oldsmobile Cutlass, Cheverelot Monte Carlo. Alot of the parts in these cars are interchangable.

The Olds 442 came with a duel exhaust system. So did the Monte Carlo SS. The Turbo version of the Buick also shared a duel exhaust system. With some light modifications, any off these systems can be made to fit onto an N/A.

The 'Y' pipe on these cars, (which came after the cat), splits off into a duel exhaust system. The trick is in the flange on the back of the cat. Some later N/A cats may just bolt on to a 'Y'-pipe.

The cats on Monte SS's and Buick turbo's won't work with an N/A because both ends of the cat have bolt on flanges. The earlier N/A's had a ball flange on the rear of the cat. I believe that the 442 'Y' pipe may work with this type of cat. All and all it's just a matter of finding the right cat.

Once you do the choice is in mufflers, (offset or inset). Tail-pipes, Monte Carlo SS or 442's. You can buy a cat-back system which is the same principle, (Hooker makes 'em for the Buicks). They are more expensive though.


I attached images of the systems with this post. Advance Auto still sells the 'Y' pipe for the 442 for $84.00 and the tail-pipes, ($27.00 each). :cheers:

 

[Buick Runner]

Thanks for the info Freddie you really know your G-bodys! I think maybe the best thing I should do is stick wityh the 2 in dia pipe but I will have it mandrel bent also will put in a high-flow cat and muffler. I just read about how nonUS DeLoreans would make 170 HP since they had no cat but the US ones had to have cats and that lowered them to 130 HP so that shows cats are a mess. So I think a high flow cat would be a good improvement, now they make 2 direct fit cats, one for N/A V6s and another for Turbo V6s which would be better? it does look like they used different hangers on the two different types of cats.