I've had Revo stage 1 on 2 Mk4 Golfs in the past, & they were absolutely trouble free. The 1st one was a 150bhp Ko3, & yes it did run put of puff a bit at the top end, but it kicked like a mule when boost came in, & was great fun. The 2nd one was a 180 bhp Ko3s Anniversary, & that kicked in...