extrusion honed RB25DET exhaust manifold

[carlo]

Was talking to john at unique autosports and he showed me a few manifolds that they had extrusion honed.

They did a flow bench test before and after and the honed manifold flowed alot more. The average before was 131 cfm @ 25 inches of mercury. After it increased to an average of 155. One thing which he said was it was alot more even as the more restrictive runners were ported slightly and extrusion honed more.

I have already replaced my manifold with a custom one, however if there is interest in this then we can organise a group buy. He suggested it would be about 500ish exchange.

I want to do the same thing to my intake plennum soon... there is no reason to replace it with a greddy big one until you are chasing 260+rwkw..

Photos here

http://www.zigzig.net/carlo/sau/

[sweetr33]

i find this really interesting about honing the exhaust manifold, still not 100% on what this means and what can actually be done. I guess it means cleaning up the casting marks and dags, cant really open the runner coz then the gasket wont watch it. Any info?