I have a FIM chip with a custom mapping done by Neil Spalding at Sigma Performance. He can change them around. Mine are 54mm cans with the standard link pipe.

It pulls really well. Jason Boswell came and took mine for a ride last week (he has a '99 996) and he said his felt like a bag of nails after riding mine. To be fair I've also added a lightened flywheel, 14t front sprocket and had the cam timing played around with so it's making power and torque lower in the rev range and more usable - hence it pulling a lot better. Neil Spalding did all the work as part of his grunter spec.

If you want to have a chat about it u2u me your mobile number and I'll give you a call.

TP