Here's what I can offer on that year bike:
Stock, a good running 125 would be a good match for this bike in a drag race. It was truly pitiful.
the stock exhaust system was quiet, but terribly restrictive. We added a complete FMF system and the difference was quite dramatic (and normally i'm not a big fan of aftermarket exhaust, many times it's overrated). The bike was still reasonably quiet ;) .
There may have been a throttle limiter on the bike, don't remember that part.
Jetting wise, the stock jetting was horribly rich, I know for sure we leaned the needle and the main. Stock it would rev about half way up and then just bumble.
Once it was tuned up, the bike was quite impressive. It started quite easilly, would idle all day without fouling a plug (even when it was rich!). Was resistant to stalling. The suspension would even handle a few jumps if you cranked up the clickers (not nearly as mushy as a KDX).