the 420a holds up fine but cannot turn the numbers consistently like a 4g63T can. But been boosting at 9psi consistently for 5 years now- not probs. Yeah one of my shop yukons - this one has a 6"BDS lift with a 3" bodylift and 36 14.5 16 MT atz. The other family truckster 4door Yukon has a 6"RCD lift w/3" bodylift on 325 65 18 Nitto Terragrapplers.