[Steve Tinker]

I think one of the biggest problems with a remote oil cooler in a Boxster is the positioning.

There's not a lot of room anywhere in the engine bay and fitting the cooler at the front of the car near the radiators would drop the oil pressure too low for the engine to survive.

On our ROW cars without the secondary air injection pump there is a little more room, but not enough to lower the oil temps significantly to make it a viable proposition.
Porsche must have got the idea of installing the original oil / water heat transfer unit because there wasn't anywhere else to put a cooler without major mods to bodywork or major components.