The point is though, If the Yoshi mid pipe is the same 1 3/8" as the stock mid pipe then you would have to use the stock header. You could have someone build you a header but it would still be the same size as the stock and not make any more power. Your best bet is to look at the other manufacturer's who offer headers and buy there slip on. Compromise your taste of looks for the additional power your after.
talk with your exhaust guy you just may have to do a little fab work on the yoshi as well. if you did build a header and keep the muffler the same you would have to neck it down to connect and might not get the air flow you want