The Normal shocks are great tbh mate and can easily take a 30mm drop but if you are seriously thinking about changing them then a set of Bilstein B8's would be the best choice.
If you do change them then make it one of your last upgrades mate because you will honestly be fine with the OEM shocks, they are pretty damn good.
As for the Pro-Kit it's only a 15-20mm drop but tbh that is plenty enough IMO, these cars sit pretty low standard.
The ABP Eibach springs are -30mm mate and do look good but expect major scrapage with them fitted, especially if you change the exhaust system.
HKS HI Power is a decent system and well priced but i'm not a massive fan of the huge bin lid tail pipe, prefer the OEM backbox or spoon N1 because they are a bit more subtle. You can change the mid section on the Hi Power so if you want performance and noise then just buy the HKS backbox and a Supersprint 2.5" unsilenced B-Pipe

pure noise!
HKS HI Power, Tegiwa Induction kit with a Tegiwa Race Manifold will see you some good gains probably 220bph maybe 225 if your lucky but the car will be running pretty lean so you would be better off getting it mapped if you change the manifold to get the best figures & power delivery (plus MPG)
Mine cost £850 for the K100 ECU, Fitment and Dyno Tuning so it certainly isn't cheap
The K Pro will set you back £1150 including everything but you really won't need it, your better off saving that £300 and putting it to good use elsewhere.
Wheels look good mate, what are you doing with the OEM set?