i honestly bought very many belts and couldnt get the right size!
let me go get the alternator pulley right fast...cause right now i have the stock one on now and the one that came with it was even bigger than the stock one......whats with that?>

 

I have the ASP Harmonic balancer/Combo Set. I did go to the track and T&T after this mod and I gained exactly 6/100ths. (no where near a tenth). It seemed to correspond with a 5 rear hp gain. Was it worth the price, probably not. I spent a lot of money on the Combo set and had charging problems for 2 years. I changed my Alternator pulley this past spring and all is fine. Its one of those deals where you do the pulley change in conjunction with another mod and you might see a few Hp. You know what, it makes me feel better that I have it and I would always wonder about it if I didnt . I would get the ASP set up because I kinda feel the "piggyback" style defeats the purpose of less rotating mass.

 

I paid 25 for one, just installed it, and I like it. I don't know if I feel a difference because I installed it along with a tuned pcm.

 

I felt some gain with mine.
I used a Crank pulley with out a Altenator pulley.
I wouldn't recommend this without a M6 though...
When sitting at stop light the headlights will dim, so I know this can't be good on a Altenator/Battery

 

my bro had it on his Z and i made his battery keep dying so he took it back