Hey guys,

I'm working on getting my 68 street legal. As you can see in my sig I have a 468 in it with 11 1/2 to 1 compression and a 1050 Dominator carb. My question is what size exhaust should I run? I was thinking of 4" but I think I'm gonna have a hard time finding anyone around here that can work with that big of a pipe. I was planning on dumping the exhaust right out of the muffler too. I was looking at the Borla XR-1 oval and the Flowmaster original 40 series. I'm not worried about the sound level. The louder the better. Give me all you guys opinions.

Thanks as always,
Bubba

 

Unless the mufflers flow as much as the pipe, they just look like a "plug" to the flow.

Personally, I don't believe Flowmaster's flow as well as say Dynomax Ultraflow welded.

http://www.dynomax.com/ultrafloweld.stm

There are a few Magnaflows which are similar in construction which should flow about the same. The Borla XR-1 Shootout race muffler @$300 per. has a 4.5 inlet and outlet and flows probably more than your engine needs.

Unless you have a 900++ hp engine, I'd suggest headers with 3-1/2 outlets and 3-1/2 inch pipes back to the mufflers. You could then expand into the 4-1/2 dia to fit the Borlas, and get about zero loss, but TONS of noise.

I think a better idea would be 3 inch ID high flow mufflers like the ones I mentioned, and use a long (12 to 18 inch) transition from 3-1/2 to 3 inches just before the 3 inch inlet muffler. A 3 inch turn down at the outlet would be good.

With the Borla you'd be looking at something like $750 from the headers back (not stainless tubing either), and with the Ultraflow welded maybe $250. Somewhat quieter, too, but still PLENTY of noise!

My $.02

 

3.5" all the way back. Most shops have no problem with this. If your not concerned about sound levels, skip the muffler, untill inspection that is.-

 

Thanks alot guys. I'm going to see what I can get done.