Scotty2000SS

I've only seen 2 companies that make the 3" catback.

Is this uncommon on the C5?

FYRARMS

XS Power
LG Motorsports
Stainless Works
Kooks

C5 Pete

I have a free one you can have. Just cover shipping.

If you're interested, send me a pm and I'll send you pics.

NemesisC5

The XS Power exits 2.5" after the muffler unless they've changed it. Read post 2 in the link below. The exterior 2.5" exit section is also indicative of the size tubing inside the muffler. Close but does not qualify as true 3".

I haven't seen or heard the Kooks but I'd like to hear a sound clip if anyone has one.


https://www.corvetteforum.com/forums...-shipping.html

Scotty2000SS

I saw that. I have PFADT TRI Y headers at the moment. I'm sending them an email today to see if they make a 3" X pipe.
XS Power doesn't impress me.

0Flowmaster Exhaust

We don't have a 3" C5 Cat-back system, but we do make 3" mandrel bent U-Fit kits in 304S and 409S stainless steel or aluminized steel that you can use to build your own. These kits will also allow you to use the mufflers of your choice so you can pretty much go for any sound that you like.

QuiksilvrZ

Can't the B&B Bullets be ordered in full 3"?

algZO6

thats what i did

NemesisC5

No, I've inquired before unless they changed their mind. They said the bullets are 2.75" but I think that is the muffler cans only with the rest of system 2.5".

I asked Corsa the same question about their Extreme system for C5, same answer...no. I've considered purchasing the Extreme and replacing 2.5" tubing with mandrel bent 3". Would be a costly endeavor with no guarantee that the increase in tubing diameter would not cause drone.

NemesisC5

The vast majority of C5Z's will be fine with dual 2.5" but if you have a larger CID engine you can benefit from dual 3". Click the link below for a good read on exhaust system tubing size and the relationship to HP. Most charts published will be extremely similar or exact to the one in the link.

http://www.exhaustvideos.com/faq/how...diameter/#easy

Scotty2000SS

I heard back from PFADT. The end of their X pipe that connects to the cat back necks down to 2.5" so it doesn't really make sense to get the 3" system.

I guess I could get it fabbed if I needed to? Or sell the PFADT headers and go with LG Pro and Big 3"?

MAJ_Charlie

I've got the LG Big 3 on mine. Here's how it sounded with my modified 346.


Here's with my 416 build.

NemesisC5

Any company that doesn't manufacture a catback along with headers and mid pipe will neck down to 2.5" to match up to 95% of all cat-backs sold and oem exhaust for C5's/C5Z's. Some minor fabrication will need to be done to accommodate a 3" catback for the vast majority.

MAJ_Charlie

Very true. I have Kooks 2" headers with their 3" pipes, but of course it didn't match up correctly with the LG Big 3 OTA pipes so I had to get "creative", but it all works. Guess it's their way to get you to buy all of their components. Problem with the Kooks 3" exhaust was over $1800. LG didn't have 2" headers...and of course everyone's headers, cats, and mid pipes only works with THEIR stuff.

grantv

Just curious what you have for a motor to want 3" cat backs? Unless you're pushing some bigger cubes and/or HP, 2 1/2" should be good for most any NA 5.7L motor I think. Perhaps the mid section could benefit from 3" pipes, but by the time the exhaust gets to the rear section it's cooled sufficiently to work fine with a smaller diameter.

Scotty2000SS

I'm all about not leaving anything on the table if possible.

Cheesecake 07

At 490rwhp...my twin 3" cutouts were worth pretty much nothing over the factory Ti axle-back. Waste of $700...pisses me off to this day.

Thats why they dont really do the 3" axle-backs. Worth nothing powerwise over the 2.5" set ups....not until you make big power anyway.

Scotty2000SS

Really? That's hard to believe.
Who tuned it?

grantv

Can't see why it matters who tuned. 3" is overkill for up to 400HP range as far as anything I've ever read. A few people in this post have made note of the same.
Unless you have bigger cubes or FI, 2 1/2" should be more than fine, particularly once you get past mid point of the exhaust system. If 3" were advantageous vendors would be all over them.

NemesisC5

Read the link below for a few eye openers regarding flow as it relates to tubing diameter and surface friction. Getting down to the finer details of exhaust design.

http://forums.hybridz.org/topic/8194...metic-for-you/