If you go down to 42 you will find the bike will struggle to maintain speed on long inclines or headwinds. The gearing will be too high unless some performance upgrades are made.

I think the DR200 exhaust will fit but it'll be expensive to buy new. I'm very happy with my Xian racing universal stainless can. It's lighter, should last years and there's a performance bonus due to the loss of the catalysed factory silencer.

Read all about it on this thread:

http://www.mychinamoto.com/forums/sh...highlight=xian