I haven't seen anyone with em, waste of time? I was thinking about doing it on the alt seen as its cheap and easy. What's your guy's opinions?

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2004 White CompG CAI, 180* tstat, 104s, 3.5", Tuned. 0*kr WOT

i had them on my first gtp
no real notice in power
just another thing to add to the ole' mod list

but it still has a unique cool factor to say, yupp, i have underdrives

but fyi you need to take the alt to a shop to get the alt pulley pulled and pressed on, and then even w/ that (at least w/ the old o/d) pulleys, you'd burn up your alt faster

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I didn't have to have my alt UD pulley pressed on. I just used a box wrench and a torx bit. Took a whole 5 minutes and I've been running it on the same Reman AC Delco Alt for the past 5 years or so. Maybe the alt rewire I've done helps the longevity but the power system in my 14 year old GP has been going strong, including the same battery that came with my car when I bought it used 7 years ago.

UD pulleys are just another little mod to help out bigger ones.

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2006 Phantom Black Metallic M6 GTO
As for the Grand Prix:
|Powrtuned|
|PLog and 3" DP with no Res|
|Full GXP Brakes and 245/50ZR-17 tires|
|4.2" SSM90 Setup with L67 TB and Injectors|
|Full Suspension with Vogtland/AGX and GMPP Handling|

2004+ are pressed on..

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You more than likely wont notice at all. But they do make a small difference and in combination can add a couple ponies, they are more noticed on record setting because every little tiny thing matters then.

The other place that under or over drives can make a difference is when turning high rpms they can help the life of accessories by not spinning the quite as fast. Or in like the water pump don't need to spin that fast to keep enough coolent flowing. So guys will run an underdrive to slow it down ( the energy used to spin the pump and the extra resistance can fee a couple horse too).

That is not to say we NEED or don't need depending on your goals. Just what they do and
are used for

sent from my driod x, via my fingers through tapatalk

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2001 white gt coupe with enough crap to make it run mid 13's with 3 bad pistons
2002 40th GTP sedan mostly stock

Alright good to know guys, thanks

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2004 White CompG CAI, 180* tstat, 104s, 3.5", Tuned. 0*kr WOT