"pocket porting"

Alright my mechanic/friend is telling me to "pocket port" my head(exh side) and TB. He's telling me that by stuffing a rag in the head and opening up the exh ports 3cm or so and doing the same to the TB(elbow...stock on a 93). I will get large HP gains. Now I know porting the turbo o2 houseing and exh manifold will give signifigant gains but Is the "Pocket port" really going to help? Will it hurt the car in any way?? I'd of course port the manifold and turbo to match.

Thanks again

are you saying he's going to port the head with the head still installed??? that sounds like a recipie for disaster in it's self.. regardless if he screws up a porting job or not (which is possible).

He told you that by stuffing a rag into the head that he will keep any chips from getting into the cylinder? <interesting> How about see if he will guarantee his work and replace/fix the engine, just in case something gets past the rag (which could wreck the cylinder wall, valve seat or seal, etc)

1)It is best that the head is removed but as long as the porting is done to the exhaust side only it is of little consequence...just clean it out well.
2)3cm??wtf? there is about a half centimeter to work with...
3)it does make a difference but... you've got to do lots of manifold porting to match. here's a rule of thumb. for every minute spent porting the aluminum head you'll spend 10 on the exhaust manifold.
It's lots of work any way you look at it.
Well worth it.