I have the Kooks 1 7/8" and I have 0 fitment issues also. I actually just posted on another board about how they did the header, exhaust and IC piping on a friends 71 twin turbo Z28 and just going by the quality work done on his car, I wouldn't buy anything else .
You may want to give TByrne a call also about the Kooks, they had a sale going on when I ordered mine.
alot of them wil fit noproblem you just have to deside if you want shortys or lts . myself i went slp lts and no regets and with the corsa good combo. best info if you do them yourself have a friend help makes life easyer. good luck. tbyrne is where i got mine.