the big bore is great for 88kits but for larger kits the 4.1 but that doesnt mean either is better, just different applications. To clear it up I have the big bore w/ 88 kit.
If your going to spend $200 + for a pipe i'd go with the Yosh.,a very good pipe for around $230.I had the FMF,BBR,Ti-Force and now the Yosh and i like it the best said the dyno...lol. But if your looking for a good pipe at a very affordable price then yes the FMF is a good one,but go with the big bore,