Just wondering if anyone's successfuly opened up the tb port on a cobra intake to 70mm. Someone told me that you would bore through to the coolant chamber in the built in egr "spacer"?
Extrude Honing involves pushing a aggresive sand mixture through the intake porting and polishing in the same step. To be honmest I am not sure how far it is opened up at that diameter, the intake ports them selves were opened up a fair bit. www.extrudehone.com
I opened one up to 70mm as a port match 1" in with no issues. I know TMOSS has done a fair bit of porting on the Cobras, he may be able to give you a good answer as well.