Differences in 2 vs 3 Underdrive Pulley kits and is a tune needed?

thomasusmc · 07-02-2009

I have been searching prvious threads and posts about underdrive pulleys for my 2008 GT. I've read and researched pricing and brands, but I havent been able to find out the difference in the 2 or 3 pulley kits. I see that some manufacturers have 2 or 3 pulleys. I understand that if more pulleys are underdriven, then it frees up more horsepower, but is there turly a difference?

Also, will I need to retune my car? I currently have the tune installed in my signature, but will it negatively affect the tune? If so, how great? If I return the car to stock, will the pulleys still require a tune? I can't find anything on the various manufacturers site stating whether or not I need to retune the car.

I had UDPs on my 97 V6, but this "drive by wire" stuff is complicated.

**pcfrisch** · 07-02-2009

Some come with idler pulleys, which are not needed.
The UDP's free up around 10ish HP.
No tune is needed.

thomasusmc · 07-02-2009

So i do not need to adjust my current 93 octane tune? I just want to make sure.

**stlwagon** · 07-02-2009

Correct... There is nothing to adjust.

thomasusmc · 07-02-2009

thanks, I think I'm going to get them.

**stlwagon** · 07-02-2009

Just make sure that whatever set you get is SFI-approved.