Is it good, bad or alright to go from 2.5 downpipe to 3 exhaust? im going for 300whp so nothing to intense.

 

yeah it should be fine you just need the right size collectors. why not run a 3" downpipe?

 

theres is nothing wrong with running from a 2.5" dp to 3" exhaust but as boxeocampeon said, you would need the right size collectors so it would be alot easier to just run a 3" dp. Plus if you did decide to up the boost you may run into restrictions down the line with the 2.5".