Hi you lot, i have been reading all the old posts, and cant find what i need. Please read and advise. My Super 8 150 runs nice, but bogs a little on hills. I have been thinking of adding a 4 valve head and better breathing and carb (bigger Jets). I cant find if anyone thinks the exhaust is too restrictive. I find a post where they think that noise is what you get from a new exhaust. Do any of you have an opinion. Thanks.