At this point, I don't believe there is anything particularly scientific about the size or number of holes that might get the best results. Until more people try different combinations and compare results, it's pretty much a shot in the dark. That said, what DS has experimented with so far doesn't seem to have hurt anything and may have improved the drone phenomenon. If I've done the math correctly, DS's mod leaves the crossover tube approximately 8% open.

As an interesting side-note, while in Daytona, DS and I spoke to the Cobra rep about this subject and his opinion was that closing off the crossover tube improves sound but possibly hurts performance. School is still out on that one as far as I'm concerned. In fact, before I did the mod on my bike, DS and I did a side-by-side roll-on comparison and also compared gas mileage and he came out slightly better on both accounts. Since doing the mod on my bike, we haven't checked again but I'm sure we will soon