Hey guys.

Has anyone had any real world positive results going from a 3 inch catback, like say, a flowmaster one, to a 4 inch catback like a mufflex system? (twin outlets)

Something in the 400hp range?

Any noticeable difference? Or money better spent elsewhere?

*no opinions on sound please - numbers only

Thanks!

 

I went to the Mufflex 3 1/2" and noticed a difference on the dyno. I did two things at once, the Mufflex and an electric water pump. Picked up 27rwhp. I attribute most of that to the Mufflex.

For the vast majortiy I think a 3 1/2 inch cat back would fill the bill and the clearance is much better than the 4". A 3 1/2" cat back would be more than enough for a 400hp motor.

Edit: Just saw a post by Dyno Don about making a 3 1/2 inch cat-back. That would be the way to go.