Transmission Oil cooler ?????

Gady all. I am currently in the middle of my suby conversion into my 86 caravelle and need some assistance with my Auto gearbox. All of the guys in the US recommend putting in a external oil cooler due to the higher rev out put and horse power difference. Chatted to a couple of transmission guys and some VW mech today about this and they thought it wasnt a good idea due to lose of oil pressure in the box. Has any one had any experience with this......Thanks

shouldnt need it if the stock flywheel and torque converter are used as the cooler is built into this

Yeah thats what the Guys down at Production Automotive said.