HoBoJoe

Also get a pair of the GT3 front brake ducts, they're around $7-10 each from the dealer.

RobC4sX51

Neb

I went through the same thing last winter after picking up my 987.1

The mods I did are:
-Mantis sport underdrive pulley
-mantis sport deep sump oil pan
-sparco race seats
-heigo half cage
-6 point harness
-bilstein B16 coilovers
-18" with Bridgestone RE71R

Ran beautifully all year, except for some smoke after a hot run.

I just added the Motorsport AOS and Tarrett LCA before storage, can't wait to try it next year on track.

I guess to answer your questions, Mantis sport have tested the underdrive pulley and they race with it and never ran into an issue even without the PS cooler.

bldn10

I added a fin-type PS cooler in front of my center radiator last year. As I recall there was an extensive discussion on Cayman Register about them, including photos and how-tos.