I had 2005 People 50 2T and the OEM exhaust was not as restrictive as later models. I assume 2002/ 2003 would be similar to my experience with 2005. I think the 2002/ 2005 OEM exhaust will be similar to aftermarket stock exhaust like Silent Sport.
My 2005 exhaust worked very well, but like mclark999 said, an expansion chamber exhaust will give the most power.
I still have my 2005 OEM exhaust, send me a PM if you would like to buy it. Cheers