R_Yates69

As the title states, I'm wondering what the benefits and disadvantages are of an Underdrive Pulley for a 99 WS6 M6 with heads, cam, intake, headers, exhaust.

LilJayV10

iTrader: (39)

There was a thread on here last week that some people have problems with the ASP pulley. At higher rpms somehow it creates a miss or some sort of vibration. I know there are probably thousands of people out there that use them but some have had problems.

vettenuts

iTrader: (4)

ASP has been linked to harmonic issues and broken timing chains, I would look elsewhere for a new damper if it were my car.

R_Yates69

any examples or suggestions?

SOMbitch

iTrader: (8)

ATI is pricey but the best. March on my car kinda heavy but 45k no issues...Lots on here run Powerbond and SLP.

darooke

iTrader: (13)

i used slp udp with no issues.

BrntWS6

iTrader: (7)

I'm no fan of SLP in general but their UD pulley is well made.

dannyz

I have run the slp pulley for 40,000 plus miles w/o any issue's whatsoever.
Well made, but pricey.

Steve Gunn

I run a 10% ATI.
Some people say run 25% or nothing.

SOMbitch

iTrader: (8)

^^^That ATI is LIGHT and rebuildable too. Maybe I can swing one my next build..... They now make a 25% too.....

cowboysfan

SLP here for 0ver 50k plus miles.... no issues here!

CranMaro99

iTrader: (10)

So the PowerBond and SLP pulleys are identical, but just with a different brand name on the product, right?

I ask because there are a few really good deals on the powerbond right now.

lusting4ls1

iTrader: (15)

if you are talking about pro and cons of just an underdrive pulley in general, then its definetely a cheap mod that you can feel. The only downside affects are if you drive in a lot of stop and go traffic in hotter temps expect your car to run warm to hot. also when coming to an idle at night with the your lights on, they will get dim and then brighten back up when you take back off. also if you have any kind of upgraded stereo system, expect to upgrade alternators too. thats what a pulley does, slows down the accessories.

if these are things you can live with or its not your daily its definetely worth it. i had them on my old mustang and got annoying to me, so thats a few ponies that im willing to leave on the table for my fbody.

BrntWS6

iTrader: (7)

You shouldn't have any charging issuses, but if you do you can just put an overdrive alt pulley on.

nichoms

iTrader: (1)

I'm not a big fan of UD pulleys. Minimal hp gain and wouldnt work to well with my aftermarket stereo without an alternator upgrade.

Not worth the money in my opinion/situation.

Jon@Texas-Speed

iTrader: (18)

It's pretty rare to have charging issues especially if you have a cam in the car and the idle is raised. You might see an issue with a big stereo but that is about it. We have run just about every brand out there and it's very rare to see an issue out of any of them. Typically a solid 8 HP gain to the ground can be expected.

Jon

SideStep

NHRATA01

iTrader: (10)

I've been running an ASP (old pre-SFI model) since about the time of my forum join date and put 40k miles on it. Never had a single issue. Have never seen a case of a car running hot at idle due to it. Only heard of voltage drop issues on stock A4 cars due to the low idle, in which case overdriving the alternator will work.

SSCamaro99_3

iTrader: (1)

Mine has been on the car since 2003, and about 15,000 miles. No problems to report.

R_Yates69

I do have an aftermarket sound system. 800W Digital Amp, two 12's and a DVD player...

So by the comments above, and given my stereo equipment I should stay away from the pulley?