A good improvement will be taking that Jackson Racing TB and throwing it as far away from your engine as possible . I take it you haven't got it fitted yet. Reason being is that those throttle bodies (by the way I've tried a CFM one which is probably the better one and the JR one which was CACK) are unnecessary unless you go forced induction and the standard throttle body is good for 170bhp anyway.

What happens is the TPS doesn't sit right and makes the engine run like a bag of rusty spanners going around a washing machine. The throttle stop isn't quite right either and basically they just will not run correctly . Countless number of posts on the FFOC about shitty JR throttle bodies. So if I were you, get rid and get some money back.

Ahh now that is out of the way, engine is not poo AT ALL! I have a 1.8 focus and to be honest, there is nothing wrong with their engines. Just because everyone on here has super dooper cosworth engines and CVH engines with gigantic turbos from the Fred Flinstone era doesn't mean you should feel intimidate or feel like you have an inferior engine.

Cams will get you a nice improvement but get the cams in and then get the car mapped. Also consider some vernier pulleys (I have Kent Cam Pulleys...very nice!!). Also, a 4-2-1 Manifold will see you get some very nice gains all across the rev range. Best one is the ST170 manifold but is a bit harder to fit than others due to power steering clearance issues but Millitek and Piper do a 4-2-1. Stay away from the OBX 4-1, stories about cheap quality and cracked manifolds surrounding those.

As for brakes, the rear disc conversion is a good idea although how beneficial it will be I don't know. I don't think ST170 brakes are quite necessary unless you will be doing trackdays or something or running close to ST170 power but the standard brakes with decent grooved discs e.g. black diamond or tarox and a good brake pad compound along with a good bleed if the brake fluid hasn't been changed for 2-3 years should be fairly adequate imo.