The IP2 pipe fitted my FF Cag after I cut off the muffler and welded on a 45 degree angle onto it, and used a KTM exhaust bracket and lots of rubber washers. It now has a BiZeta muffler.
It's a great performing pipe - can't fault the performance. But it can be a bugger to fit.
If you use a stock carb, you're gonna need to use an adjustable main jet (or go to
www.scooteparts4less.com - they sell different size jets for the stock carb, and their service is very good. I get stuff from there in Cali to here in the UK in 4 days - nice.
You'll defo want a decent air filter as well, without a doubt.