I have the FI LTHs and 18" Res SS exhaust. Love it. Quiet on cruising, but still audible enough to know it's not stock. When I get on it, she roars to life.
Although, OP I find it hard to believe you did a search for F.I. info and didn't find enough... There are countless threads over it, not to mention the 2 main FI CBE threads, and the FI LTH thread...
