I've searched extensively and browsed dealers "claims" of horsepower increases. Advertising seems to indicate that their may be a slight difference.

For a simple bolt-on car(MBC, 3" HFC, 3" cat-back) that is going to be dyno tuned (flashed) next week, would a 3.0" downpipe provide a significant advantage over a 2.75"??

How about exchanging the 3" HFC for a 3" test pipe?

Thanks for your input.

 

no it won't until you start upgrading the turbo.

 

For your mods it won't make much difference at all

 

it would add exactly .25in more room for air to flow which will be a minimum increase in horse power and will notice a little more lag then the 2.75in down pipe.

 

smaller DP has shown to have a little better torque but will start to cause restriction at 310whp in the mid to high rpm .