99 and up performance

i have owned a 99 grand am se for about a year now and have loved it greatly but i was wondering if anyone has either had a light weight aluminum underdrive crank pulley or had a friend with one just wondering if they are as good as they are made out to be i found this sight had one
http://highrevemotersports.com for 160
also i found a sight for a diffrent muffler (it claims that i actually speed up the exhaust that is coming from your engine) www.aero-turbine.com (http://www.aero-turbine.com) and wanted to know if anyone has any ideas good or bad about this
if any one has any other performance sugestions please let me know \
thanks

the underdrive pulley is a pretty good mod. PPL report more oomph at the low rpms. For the turbine deal....junk.

What motor? If you have the 3.4, Fast forward performance makes a good one

http://www.fastfwdperformance.com/

so does rsm racing

http://www.rsmracing.com/

if you've got a 2.4 I think andys auto sport has one for that

http://www.andysautosport.com/

first of all thanks and i drive a 3400 grand am. although talking at work a coworker said that the harmonic balancers are the weight they are for a reason being dammpen out vibrations and that the lighter ones can tear up your engine

That is true. But no one I know has experienced this. Go search over on grandamgt.com. There is some more technical stuff over there.