Right i have cat back system, walbro pump, gtec, K&N, boost controller, boost gauge, fuel pump relay mod, BKR7EIX plugs and bailey dump valve, my standard turbo is well and truely knackered so i thought may aswell upgrade and go for some decent power, so just wanna know exactly whats needed and which bits will need an expert, i can happily remove and replace turbo and what have you but was thinking along lines of will any welding need doing for de-cat or downpipe if welding is invloved i will need help also obviously will need re-map where as if all is bolt on goodies then i'll be fine so just wanna know the recommendations please guys.

for starters a front-mounted Intercooler...but check out the FAQ tuning section

front mount Intercooler, injectors, fuel pressure reg, turbo, fuel pump and relay, good free flowing exhaust, air filter, and a good remap

About £2,000

and uprated brakes and uprated clutch which is probably another £1000.

for a reliable 350bhp (on top of the mods you already have)

GT28RS (0.86) or GT2871 (0.64)
3" downpipe (or maybe 2.75" from Blueflame)
3.8bar FPR (or possible 16VT injectors as well)
Helix organic clutch
ProAlloy FMIC
FC Performance stage 3 map

so that's your power achieved, but as already mentioned, you would be well advised to uprate the suspension and brakes to cope - 350bhp will give you a 0-100 time of just over ten seconds and will take you onto around 170mph - the standard brakes and suspension are just not built to handle the forces you'll get at these speeds - so...

strut brace
new wishbones (possibly polybushed)
uprated springs and dampers
uprated discs and pads

To build a safe and reliable 350bhp Coupe, I reckon you're looking at closer to £4,000

I agree with Nigel

One last advice steveo, don't forget 350HP will be at the limit in terms of reliability with standard internals

Easy!

Ferrari 512 BB . Good for 355bhp. Here's a nice one on Pistonheads