I am building a Lotus 7 replica with a 12A street port. The exhaust will be a custom unit that will run outside along the frame. Here is what I am currently planning on using based on available parts and size/space restrictions:

2" Primary tubes, as long as possible (longer = better torque?)
Y collector - 2" in / 2.5" out
Car Chemistry tube muffler w/ 3 inserts (2.5"in/out - 3" dia x 12" long)
2.5" turnout
I'm also looking at the Dynomax Spiral Flow which is a 4" dia unit vs the Car Chem 3" unit

Should I run 2.25" or 2.5" pipe for the primaries?
Anybody have any experience with the Car Chemistry or Dynomax muffler?
Any other comments/suggestions?

Thanks.

 

oops....That should be a Moroso Spiral Flow muffler

 

i like dynomax super turbo mufflers. they are cheeper than most mufflers but that is good. rotarys melt mufflers pretty quickly.

 

Don't know the numbers off-hand, but the racing beat catalog has lengths for optimal exhaust.

 

Anybody know what those optimal primary lengths are?

Thanks!