pauldana

I went 2.75" for better clearance and increases over 2.5"

Les

I think you have enough good info about performance to decide whether it's worth it in that regard. I'll just add one thing. Based upon conversations I've had and what I've read, the interior sound level and the possibility of drone both go up noticeably when you have a 3" system. That being said, if I knew I'd gain enough performance I'd live with that. However, I just use my 69 for short hops, not trips.

Ironcross

four inch.....on a 574 ci all aluminum supercharged Hemi.....no ground clearance problems as the floor was raised to accomplish that size

C3 Stroker

All 3" systems for C3's are custom made. As previously stated, any good exhaust shop can make one for you. Magnaflow has the mufflers you need with 3" inlets and outlets.

I have a set of these....http://www.summitracing.com/parts/mp...9/media/images

Also, 3" tips which look like stock...

63mako

That is the ticket.

Crepitus

A couple sizing charts if you root around here;

http://www.flowmastermufflers.com/index.php?page=54

ajrothm

Do the 3".. Do it right the first time so you don't have to re-do it later. Anything 450hp or more needs a 3" system for max performance.

You never know, you may throw some nitrous on it down the road build a big cube SB and atleast you already have the exhaust done.

My buddy built a nice 3.5" system with a plenum chamber instead of an x pipe for his 420" SB. The engine made 640hp. Car runs 136mph thru the muffs and its quiet as can be...

n076720

You brought up a point which I hadn't considered and that is the use of an H or X pipe configuration. My current exhaust on the basic 350 270 HP motor is straight from front to back without an H or an X. What purpose do those configurations offer and should I have one as well?

n076720

I found my answer. Its to share the mufflers across both cylinder banks and H pipes give better low end sound, throaty rumble is what was said, and X pipes don't necessarily. For a street machine there isn't much of a performance difference but an H pipe is easier to install. An exhaust plenum is a pretty complicated piece of equipment with variable springs to adjust flow so I think that's out of the picture.