I am not sure it is a simple as a timing issue. I could be, and if that is the case, have it timed. It is a very easy procedure, you could do it yourself if you had a timing light, the specs, and the directions. It could also be a fuel issue. When you change the exhaust system, you change the amount of air and fuel that flows through the engine. That is the main purpose for doing it. You increase the air flow, you increase the horsepower. But, with an increase in air, you also need to increse the fuel, as well. This needs to be done by someone who knows what they are doing. Have it checked out, because a fuel mixture that is too lean, will burn your motor up. Too rich, and it will be sluggish, and load up with too much fuel. Have someone check it out for you, or learn as much as you can about it and try to tackle it yourself.I hope this helped.Stevo.