general buying question

I am finally putting the money down for the upgrades I have been wanting for a long time. I am going with the Steahly 12 oz Flywheel weight and FMF Gnarly exhaust. Heres my question. I can order both of these products directly from Steahly, but the decription of "fit" for the pipe says "fits most 2 strokes." Now I have read all of the allignment on FMF's site and numerous others, you narrow it down to the year make and model. If I am being clear on my concern, will this be an issue with fit? Are they correct in selling one product to fit all? I would be more than glad to purchase everything from as few places as possible. Any thoughts?

Thanks,

Alex