Exhuast Port Sleeves
 

What is the purpose for the sleeves and can they be removed? Would there be any reason to remove them? Would the exhaust flow better without them?:102:

Those sleeves get Very hot to burn off extra exhaust gases. A emissions thing. They can be removed, although I've read to be a diffacult thing. They don't really restrict much. Removing them won't benifit enough for the work requird. (Please forgive my spelling) If you really don't want them I sugest a P90 or N47 head. As they don't have them.(correct me if I'm wrong) all in all. Leave em be. There fine.

x2 on that. :D

the n47 has them. you need a e88, or n42, or e31 then they are gone. but then its square port exhaust, and a different header. manifold stays the same

I've wanted a E88. I heard they flow pretty well. And the large valves.

Thanks for the info. I'll leave well enough alone.