I just got a 2008 Tomos Targa LX with a 64cc kit. It wasn't running, but with a little fortitude, I conquered the problem (Flooding due to a bent float bowl "float pin") This beautiful machine has a Biturbo exhaust that came with the "Airsal" kit.
First of all - It decelerates with a decided jumpiness. It accelerates fine, and has a top speed around 45 mph, (Not sure, because speedometer is very erratic), and I believe the machine is way too loud! Its hard to describe the deceleration but sort of like: Wow -- Wow -- Wow -- Wow! and the machine actually jumps a bit with each "Wow".
I'm curious to hear if anyone else has had similar results, and what if any fixes, ideas or suggestions might be forthcoming.