Early on (like 1000 miles) I drilled out the back two plates with 1.5 inch holes and then put 3-1/2" holes in the second plate (I miss-placed the first hole so only had room for three instead of four I was going for) I ended up with a brilliant sound and it just got sweeter over the years as they get louder as time goes by.
I modified the air box and added a high flow filter and I took mine straight away to the dealer because I didn't want my warranty skewed, they told me it didn't need to be re-jetted and just raised the needle (if I recall correctly to richin it up)That it did and it has run great since, I have 28,000 miles on it.
Modifying the air box is a must as it changes the air flow going in to match that going out and keep the air/fuel mixture where it needs to be. That was 27,000 miles ago.
eddy
