Underdrive Pulley Install Guide

[Boxster586]

Originally Posted by MikenOH

Had a chance to drive it yet and notice any difference?

Hello Mike-

I did take it out for a short drive. I believe it IS the best $219 (includes new shorter belt, pulley tool, and shipping) I've spent on this car. Peppier in the lower rpms. Can't really tell above 5500 rpms. I need to get back on the track to confirm as I have zero access to a dyno.

Have a good week.

[ilikeching]

Originally Posted by Boxster586

Hello Mike-

I did take it out for a short drive. I believe it IS the best $219 (includes new shorter belt, pulley tool, and shipping) I've spent on this car. Peppier in the lower rpms. Can't really tell above 5500 rpms. I need to get back on the track to confirm as I have zero access to a dyno.

Have a good week.

Lighter rims & wheels will definitely feel the difference too, much more peppier at low rpms.

[jb92563]

Someone had said that there would be no AC at idle with a 4" UDP, so I thought I'd post my results to clarify.

I installed my Tarret 4" under drive pulley and all went well and better than predicted.

Particularly, I am happy to report that a 2001 S with the 4" under drive pulley still allows full operation of the air conditioning at idle!

Here is the Proof below:

With the Tarret UDP installed and the engine up to full operating temperature,
Ambient temperature 70 F as shown on the guage, and ~750 rpm at idle for over 5 minutes, airconditioning set at full the temperature of the air leaving the vent is ~38 F.


Tarret UDP and Original