1968CutlassSupreme

Hello All!

Forgive me if this information is available and I am just not seeing it. If it is just ignore this and (please) put the links to where it's already been discussed. Thanks.

I can't seem to find (maybe my search skills are lacking) any questions dealing with purely exhaust systems discussion. I am looking for information such as the pros and cons of an x-pipe in a dual exhaust setup verses the straight pipe setup, and I'd like to hear from those who have used each one how they set theirs up.

For example, x-pipe with flowmasters or magnaflow or pypes brand mufflers. Or Dual exhaust without the x-pipe same setup. Or mufflers that I may now know about.

What to watch out for; good companies to buy from; and bad companies (or less reliable companies).

It's going on a 68 CS.

I thought it would be good to have a discussion that covers all of this in one place.

Thanks everyone! I'm looking forward to a good discussion!

Olds64

I have an X pipe on my 71 98. They are supposed to equalize pressure between the exhaust pipes and allow the exhaust to flow more smoothly (laminar vs. turbulent flow).

Truthfully, I doubt it did much on my 71 98 besides making the exhaust note more mellow. However, since I run glasspacks that's sort of a moot point.

slade69

You didn't mention if you still have the stock log-manifolds. If yes, it does not really make any difference what you have behind them (unless turbo). If this is your situation, put your efforts to good long tube headers, that's where the biggest gains are.
If you already have a performance built engine with headers, then dual 2,5" with chamber style mufflers are what you need. You rarely need bigger with n/a SBO. With H- or X-pipe you can gain little torq/hp, but only few. H-pipe is better for low rpm torq, x is better hi rpm hp. X-pipe lowers the ground clearance dramatically. And remember we are talking only few ponies maximum.
I do not use either, because at best few hp:s and they ruin the sound+ground clearance. My opinion only.

olds 307 and 403

I have a compact X pipe, ground clearance is fine. A few of the full length headers lower ground clearance, Sanderson or Hedman shorties with custom down pipes are an option.

slade69

Anyhow the x-pipe needs to be in the middle, under the trans or driveshaft. Definetely takes couple of inches from ground clearance. I have routed my 2,5" duals very close side by side with driveshaft and they are not the lowest point of my car. Ground clearance was an issue for me because my ride height is pretty low.

bennie442s

Engine Masters has done several episodes on this and similar topics. Links are below.
-ben

olds 307 and 403

With full length headers, I can see it being an issue. I ran both my 2.5" pipes on the passenger side and used a version of this.
https://m.summitracing.com/parts/jex-sxp4ss

1968CutlassSupreme

Thanks everyone!

So, what about brands? Pypes or summit brand or magnaflow or flowmaster or etc..etc...etc?

It seems that the x-pipe tested the best. The two and 1/2 inch exhaust appears to be the better of the two. Mufflers are actually you get what you pay for. But I understand there can be fitment issues with the x-pipe system on these cars, is that right?

You guys are great and I appreciate the conversation!

olds 307 and 403

The Summit Turbo and Dynomax Superturbo are both mild. Hooker Areochamber mufflers sound awesome but are louder.

slade69

That's an interesting way to do it. How do you go over the rear axle and beyond. Happen to have any pictures?

cutlassefi

You can make your own X pipe as well from a couple of 45* pieces welded together. At that point they can be twisted so that they're actually higher up in the chassis than the regular exhaust system.
I recommend X pipe over H pipes. That video displays what I mean. I said it on here years ago.

slade69

This is a good idea I'll try that!

olds 307 and 403

The back half is a a Hooker G body cat back with custom tail pipes for my 70S. I will take a pic tonight.