2001-2003 F4i owners (prolly up to 06 too) help me out: first off does your header look like this
(1) http://www.mrcycles.com/fiche_section_detail.asp
or this
(2) http://cgi.ebay.com/ebaymotors/2001-...QQcmdZViewItem

Also hopefully it looks like number 1, if thats the case I will be looking into an aftermaket slip-on, which slip-on has a quieter tone. Not something too
loud and buzzy because i went -1/+2 and dont want to lose my hearing on the highway

 

not sure about the header, there is no pic on the first link. As for slip-ons I have an 02 f4i with two brothers slip-on, and its got a nice deep tone thats nowhere near annoying.

 

01 f4i w/ 2bro slip on, love it

 

i got two bros too, and it's awesome lol

 

Two bros. here too and loving it!!
DO NOT get a D&D if you don't wand an obnoxious pipe