This thread shows how a trans cooler is being plumbed on the 5 spd:
http://986forum.com/forums/boxster-parts-sale-wanted/32117-boxster-spec-5-spd-transmissions-sale.html Eric could fill you in on the details.
At 170rwhp and no wheelspin a stock 5spd is pretty reliable in Spec cars. Add a 3.4L or overly stiff rear springs and get a lot of wheelspin and a hot, unhappy trans. Adding a cooler and LSD does seem to improve reliability but a wild-eyed driver slamming gears in the heat of battle can still do a lot of damage.
My trans was replaced at about 96k with another stock 5spd. It had a failed pinion bearing that was likely a result of inside wheel spin on corner exit.
