I’ve owned a mk5 golf gti for the last three years. Same engine. Best car I’ve ever owned. Oil consumption is no more or less then any other car i’ve owned. Things to check are oil pick up pipe in sump, these apparently get blocked up, mine was checked and wasn’t blocked. Divert valve, make sure diaphragm is not ripped (loss of power results) and while your at it replace for a revision G one. Has fuel pump cam follower been changed (it’s a 30 quid serviceable part, get it done with yearly oil change). Speaking of oil use Miller’s nanotech at 5 40.
After all this take it to r tech in Hinckley and get it mapped. You will see a reliable, healthy 250 bhp and 300 lbs torque from a stage 1 map.
Do it you won’t regret it.