corksport's downpipe is not 3". Their downpipe is 2.4. The only thing they offer in 3" is the exhaust itself. There may be a small gain, maybe slightly quicker spool but if you already have their downpipe, I would stick with it. Really, anything is better than the stock downpipe
Paid, I hope I don't need the 3" to 2.5" adapter... I'll get a custom exhaust w/ high flow cat mid pipe (all 3") down to 2.5" exit with stock exhaust tip.