Anybody ever install the CFM 2 pc. aluminum underdrive pulley kit on their svtf? I was just checkin it out on CFM's website and it says it will gain 3-5whp... Just wanna know if it is worth buying.

Nope it sure isnt. Spend money elsewhere.

I agree.

being no two engines are built exactly alike, they each react slightly different to mods.
I've never seen a dyno showing much of a gain, if any from these. altho some will say they felt a difference (aren't minds playing tricks on people wonderful?).
for the cost, install time, etc. they aren't worth it for what little, if any, improvement you get.

There is lots of info on this site about the pro's and con's of a underdrive pully kit. The majority seems to be against it. Do a little research and then make your own decision.

A lot of people say that these will damage your engine but this is not true.

No one has come forward and said that there engine has been screwed up by underdrive pulleys.

If these products are so dangerous why do CFM, Massive speed and FSwerks (focus sport) all sell them.

A lot of companies that sell underdrive pulleys all claim they make a little more power but I don't think they do but that's just my opinion.

I have a 04 svt, had them install about three months ago. There is a small amount of HP gain. Like you said 3,5 hp.

i wouldn't really call it horsepower gain. more like increased throttle response, easier rev matching, less bog when a/c is on... so if those are what your looking for its up to you...

Isn't the main benefit from the lightweight pulleys to reduce the parasitic drag caused by the heavier pulleys and thus increasing overall response?

I doubt a power increase at all, but it will definately allow the engine to function a hell of a lot more efficiently. Plus, it's cosmetically pleasing to look at aftermarket pulleys. :D

These are the same as the ones for the Zetec.
I have a 2 piece set from Massive and both pulleys together weigh only a small FRACTION of what either of the stock pulleys weigh.

Mathematically, there is a pretty good difference here, but with our motors, it just doesn't make much of a difference. Our Water pumps spin pretty freely, Our alternators don't have that huge of a load to carry. Slowing them down won't do much and the weight of the pulleys is insignificant to the crank they're attached to.
Were there any real gains. Hard to say. If anything, It's a bit smoother with the AC on...

More info...I posted my 0-60 time decrease with the UDP's (7.61 sec, stock, 3run avg, 7.18 sec UDP, 3 run avg) and recieved all kinds of grief with that, so I won't post those again, but I will voluenteer some fuel economy data:
Stock - 5 sample avg: 27.77mpg StDev 2.2
Mod Cal - 42 sample avg: 27.90mpg StDev 2.86
ModCal UPD -19 sample avg: 28.68mpg StDev 3.06

This is random driving data covering 4 years of FE data. Combined driving, nothing special, poke holes in the data all you want.....but data doesn't lie (!!)
No need to comment, I know these hp's don't show up on the dyno, but that was the data...