I purchased an 05 sv last year. The previous owner had desnorkeled it and put tank risers in. I put aftermarket mufflers on it because it had no mufflers when purchased. I know that these modifications with no tune will gut the bikes low end power. However the bike seems like it's gotten slower. I just broke 40,000 miles and have done spark plugs and an oil change. Is there anything else I should be looking to service, valves? Or does having no tune gut the bike that much and it just seems slower because I've gotten used to the bike? Any info or opinions are appreciated