Considering you are in the UK , and in close proximity to SRD ; I suggest you try get access to a BPU car and a to4z car , go for a spin ; hell of alot cheaper than modding your car to figure out what you may like
As these cars a getting on , I would also assess the overall condition of the car, its core foundation , Suspension condition, top mounts , brake lines , general underneath condition , bearings , crank pulley age, oil pump , water pump, engine seals ...
I must be 10K in the hole to get the basic components refreshed, after suspenison refresh, suspension top mounts, underseal , boot lid required attention , new crank pulley, new oil pump, water pump, clutch, diff seal, rear main seal, brake caliper refresh, leaking oil pressure sensor, new radiator .... these are serviceable items , I would not nessicilarly wiat till something fails, mileage , age , in some instances visual inspection will dictate what needs replaced
I am only getting into a full engine refresh and single install this month , I easily have near 15K in parts sitting at home; if you do not have the basics in roadworthy condition , throwing more power at the car will only accelerate their shelf life and may even result in catastrophic failure
Going fast is not cheap , if you have to cut corners ; you need to re-asses your budget and hold off till you have a healthy budget