So who's had their exhaust manifold ported and polished? I read about this in Turbo Magazine. They sent their manifold to ExtrudeHone to have it done. Does anyone know how much it costs to do this and how big or little the results are?

Retail cost from Extrude Hone's website is $385 for a four cylinder exhaust manifold. Don't know how much the hp gain to be had.

Steve

It depends on the type of manifold. A cast manifold like the GTIR has alot to gain.

Steve

Holy Crap! That's a lot more than I thought it would be. Is there another method to getting the same results, whatever those might be?

BTW thepep, thanks for the response.

98sr20de- What do you mean by "a lot" are we talking 10 hp?

Again thanks for the replies

Extrudehone has the market cornered on that process. There really isn;t any other way to get those results, HP is directly proortional to the turbo your using, do the manifold, exhaust housing, and the j-pipe and you'd be rolling.

Extrude hone and port and polishing are two different things.

"Extrude Hone invented the Abrasive Flow Machining process nearly four decades ago and developed an entirely new kind of finish machining tool. A plastic, abrasive laden polymer, with special rheological properties allowing it to selectively and controllably abrade surfaces that it flows across."

This was taken from their website http://www.extrudehone.com/ (http://)

This abrasive material is used in smoothing the inside walls off the manifold and removes any inperfections and slightly enlarges it.

Port and polishing is when you enlarge the openings and possibly the whole manifold and would match port the head and then polish. This will increase the size of the manifold where you want to. Porting the turbo will also net some gains, not to sure how many hp's.

I think the best combination is to port the manifold and the head and then have the manifold extruded honed, not the cheapest though.

Mike