My buddy at work thinks I need to upgrade my exhaust on my '06 goat but I love the sound of it stock. Is it really worth the $ for 10 hp or so, and does it really sound THAT much better? Any suggestions on brands? Borla, Corsa, Magnaflow, etc. Thanks all, am new to the tuning game. 2 more things, is a Diablo flash programmer worth the 400 bucks? and is a K&N intake worth the 250 or so?