Horsepower wouldn't suffer so much as torque with true duals, like drag pipes good at wide open throttle. A built motor would have enough torque to sacrafice a bit for the sound of true duals.
anyone see the new rinehart xtreme true duals for 09-10 and what do you think? I was told 2-1 gives you low to mid range hp tq and true duals will increase mid to top end I guess it depends what kind of riding your doing.
I heard my first HD "Nightstick" this weekend on a new 2010 SG and like I expected from HD slip-ons it was just barely louder than OEM stock mufflers and not very impressive to me. Also don't waste you time or money on the D&D Fatcat slip on as it sounds like azz too. That's what I have on my 2010 SG and even with the CAT gone and the baffle packing removed it still isn't much louder then stock either and the rumble is only a little deeper than stock.
Just got my bike back from the dealer a week ago. Stage II 103 kit, D&D Boss Fatcat with wrapped perforated baffle, SEST, Zipper's filter upgrade for the Stage I SE Air Cleaner. Bike sounds and runs great with the D&D, performance is much improved over stock.