You have obviously done some reading up on it all and know roughly what you want to get / do . Are you after a faster zed ? I didn't really want to go fi on my zed but as you've said , once you've done the maths and worked out the bhp/ performance gains it's a no brainer . A zed with say 300 whp v one with 250whp is not going to feel vastly different and on the road dare I say it , it wouldn't be that much faster . I made 435 bhp with my set up .... I wanted a tad more .... A £90 pulley and £200 fitting / tune and I gained 30 bhp . The point I'm making with fi there is room to upgrade at a reasonable cost , which is why I decided to go this route . If I had spent 8k and only got 300ish whp I would be proper cheesed off .