How many people on here have matched the openings on their standard exhaust manifold to the opening in the underside of the cylinder heads? I have just done mine tonight and am curious as to what others have found with regard to performance, noise etc....

 

Yes. Technically I had mine done for me when I was getting the up-pipe fitted (MY02), so any effects will be combined with the effects of the up-pipe. My thoughts:
Faster spool up, a little more torque in mid range. Holds power a little better at the top end. A bit less "boomy", smoother sounding, and quieter at low revs / throttles. Probably a bit noisier, but with a pleasant rasp at high revs / WOT.

 

Did mine last year , slightly better spool up etc, basically the same advantages Hades has mentioned.



Iain

 

Thanks guys. Tried it this morning on the way to work. It certainly feels to spool a little quicker and does have a bit more "growl" in the exhaust note.

 

For me the spool up was unchanged (Dawes) but it's smoother at both the top and off boost too

My Dremel made light work of it until the iron fillings caused it to short out internally - doh!

 

dremel? light work of it?

Die grinder and tct cutter takes time..

How much do you remove.. I end up with nearly a handfull of metal!

David

 

Yep burr grinder bit for me. I also ended up with a good handful of filings. I was quite surprised how much you can actually take out.