Underdrive pulley worth it?

**GottaHaveLS1** · 03-03-2008, 01:00 PM

I've heard that install on these cars is really difficult and not worth the gains you might get. Is this a hard install on the ls1 cars? Has anyone seen dyno proven gains. I'm curious about them because I have almost every bolt on and for $200, I wouldn't mind an extra 10 hp. what do you guys think?

**Midnight02** · 03-03-2008, 01:05 PM

Given the fact that the install is a bit challenging, it's worth holding off on the pulley swap if you plan to do a cam swap in the future (do both at the same time). Otherwise, you're looking at around $200 + labor for roughly 5-7 rwhp. If you're ready to take the next step without saving up for cam/heads/etc....in my opinion, it's a worthwhile mod. You might also be able to get similar gains from a ported throttle body with bumpstop mod.....all at roughly half the cost and I can promise you the install is much easier than the pulley!

Unfortunately, since mine was installed during my cam swap, I can't really speak at to precisely what was gained (or essentially "recovered") by adding the U/D pulley.

**nhraformula** · 03-03-2008, 06:02 PM

not worth it to me

**Speed Psychosis** · 03-03-2008, 06:15 PM

I'd like to see proof of that much of a gain. The most I have ever seen on any car was like 3.

If you have a M6 get a flywheel, if anything. The pretty much do the same thing, add a little whp (but not at crank) and give better throttle response, yet don't have nearly as many side effects. Only thing is its slightly harder start/launch.

Personally I would do neither and put that money either toward something bigger in performance or a good radio upgrade.

**FSANE** · 03-04-2008, 07:52 PM

The only time its actually worth it, if you're already doing a H/C Swap. Since its already out, might as well install the UDP. Otherwise, save your money, time and energy.