Typically how much bigger do you go with your jets when you put an exhaust on your bike? I put a 2 into 1 from Dennis Kirk on my '78 Yamaha XS400. Stock size jets are 132.5 on the Mikunis. First attempt I drilled them out, it ran ok untill about 7k and it would break up, ok so too much fuel. I then bought new jets, 145 and 147.5, have the 145s in right now and its all screwed up, barely idles, won't rev, stalls if I touch the gas. I'm guessing I need to go way bigger? What size jets would you suggest? TIA!