Ok so I got an issue I need help with. Cruising in 4th or 5th if I roll on the throttle quickly and put the engine under a good load I get this horrible almost metallic top end noise, or it atleast it sounds it. Possible spark knock or something. So I pulled plugs to check them and they're getting very weak spark. I'm gonna double check them with a spark tester and new ones. But does anyone have any experience dealing with the same issue? It's an 04 1600 classic with 12k, only has after market exhaust (I know I need to get a fuel controller). Thanks for any input.