ive read post on underdrive pulleys and want to know hp/tq gains and where to buy. if anyone could give me a part number so i know i order the right thing. any helps would be appreciated. thanks in advance. (btw i have a 07 f150 4.6l screw)

 

got mine from ASP and love them. they produce full charge at 800rpm and made quite a noticeable difference in performance. i dont remember the part number but it wasnt listed for my truck. i think it was listed for an 03 expedition. i have the same truck as you (year, motor and body) and worked just fine for me

 

thanks for the info. any body know hp gains? and whats the best brand? and whats better piggyback(dont know exactly what that is explanation would help a little bit) or a whole new system? brands? thanks again

 

hp gains are 10-15hp. dont get the piggy back kit. i would go with asp but if you want to save a couple bux, i think summit has some for about $40 less but not sure on the price. i got my asp pulleys off ebay for $100

 

where can i buy asp pulleys?

 

aspracing.com of course. i have heard that the ones that troyer sells are asp so might want to give them a call. could search ebay as well

 

i was under the impression that U/D pullies did next to nothing? strange to see you guys endorse them.

 

depends on the car. didnt notice much of a gain on my mustang and ended up selling them but on my truck they made a very noticeable improvement.

 

what year truck?

 

X's 2

Now Im interested in hearing a little more about this, as I have thought about buying some a few different times.

Tom

 

Troyers website say they give 11.8hp gains and 15hp with their tunes.

Except if you ever wanted to supercharge your truck down the road the pulleys would have to go.

 

2007

 

too true

 

I found that out the hard way, but the supercharger is better

 

Troyer also claims shorty headers give 15 hp, but a member on this site proved thats not true. unless I saw a dyno sheet after install I'd say you're most likely around the 8-10 range for pulleys. nothing against mike, but I trust a dyno sheet over taking someones word for it.