Look DoNT mess with the R6 SYSTEM
the best you can do is replace the stock can with an after market or slip on
if you replacce the header and the main collector you are going to be in a whole world of financial pain..
if it ain't broke Don't FIX IT...
don't you think Yamaha did a good job in the first place???
I bet you are the kind of bloke who puts condiments on a meal prepared by Gordon Ramsay...!
If a Chef seasons a meal then it is correct and needs nothing more...
Take a look at the YAMAHA emblem.... What is it made up of? I'll tell you THREE TUNING FORKS!!! it doesn't mean as some say that they make musical instruments ( they do) it means Tuned to perfection...
If you want to up it go to a yamaha dealer and get their STAGE 1 kit.. that is designed for the job..
BTW Yamaha make 3 levels of tune for their bikes Stage 1-2-3, Stage three is a full on race bred bike and will cost you upto 3,000 on top of the bike.