Underdrive pulley questions

**jag42420** · 10-19-2006, 05:39 AM

Underdrive pulley ads claim improved mileage and 10+rwhp. Opinions? (Other than the obvious needing of a new belt)

**jag42420** · 10-19-2006, 06:09 AM

I noticed SLP has one that has raised edges to prevent belts from slipping off. Anyone had problems with here that?

**sunsetorangess** · 10-19-2006, 05:26 PM

In my opinion its not worth the hassle. It will give gains but nothing you will feel.
J

**89LX** · 10-19-2006, 05:55 PM

I think it is a very good mod with other bolt-ons. Remember you can't generally feel (seat of the pants) small gains. They are accumulative by nature and will result with more power at the end process. UD's don't make power they free up parasite drag resulting in faster windup and RWHP. Known fact with many sources of dyno charts (all auto's) to prove it. Most seem to add between 8-12. SLP sells their UD for $213 on EBay (what I have) and no belt issues yet.

2000 Z28 M6, SLP Lid, Smooth Bellows, SLP UD Pulley,
P&P TB and Maf, TB By-Pass, Front Strut Brace, Hooker CB, Predator Tune