From what I've seen and tried on UK cars,

Full race, TD autowerks, MAP performance, F5 performance, AFI, spooling fabrication, nortech and solid fabrications all fit and work fine with no issues with reference to turbo and wastegate. Just the usual relocation of fuel, water and brake booster lines which you have to do with pretty much all k20s

However, all require modded off the shelf downpipe and screamer or a custom/ home made affair. Which tbh, isn't all that difficult if you can borrow a MIG welder just for tacking.

From UK myself if you need anything