AirKnight,
IMO…The black crap build-up, totally negates the extrude hone.
Here is my post where a asked the same question:
http://contour.org/cgi/ultimatebb.cgi?ubb=get_topic&f=6&t=002393 Not much traffic on that post, but I can tell you from fist hand experience that the upper intake fills up with crap. David Z posted a good explanation in the post above. As soon as I cleaned my upper intake and secondary butterflies (also coated with crap) I felt a big difference. The car pulled much harder and the secondary kick-in was much more pronounced. Keep in mind my car had 60k worth of build-up.
Btw… all of the other 60k maintenance I did (and I did it all) was good, but I could not feel any performance gains. That said, when I cleaned my upper… I could feel the difference
.
-burg
