Haven't come up with any reliability issues yet (knock on wood). I let the car and SC warm up properly before stomping on it. Only quirk is the power and torque levels are bumped up compared to the standard kit.
I prevent detonation with this setup by not stomping on it when's it 90 degrees out. It's a shame that this car doesn't have a knock sensor that can be used to monitor it.
The tune from Rob at z car garage is conservative to prevent detonation, can't stop it. He runs it on the dyno and tunes it aggressively until it starts detonating and pulls back the tune a couple notches. There is always risk with aftermarket setups. I installed a temp probe near the Stillen manifold and saw changes of up to 30 degrees within 5 seconds of boosting/stomping. The temps stabilize within 10-20 seconds of normal driving.
The goal for me is to bump the area under the curve for more usable power for my driving (street driving, stop and go) and to sustain that power level and keep the engine as safe as possible. The impeller upgrade and 9psi bump up the power from the standard kit and the test pipes lower the peak boost (seeing 9.8 psi on the dyno and 10.8 on my boost gauge - thinking that it would be 2 psi more if I threw the stock cats back on - problem is increased heat and potential for detonation). The future air to air intercooler addition and vented hood would delay heat soak and generally lower engine temps (air charge temps).
The blown motors I have heard about seem to be from running at the drag strip or running the motor hard for an extended period of time on high boost (12 to 13 seconds haha and repeated boosted runs).
I don't know what the standards are for a boosted car in terms of how long you can stomp on the car until it blows. Maybe your tuner is expecting you to stomp on it all the time so the practical thing to do with impeller and 9psi kit is to use 93 or meth so you can run hard all the time and at the same time pick up safe power/torque that doesn't make the upgrade a disappointment. For my setup, I feel my power numbers are low but I believe that they are safe and right now safety is higher on my list. I wasn't expecting much from the craptastic 91 octane so I wasn't disappointed by the number. The car feels great though.
Z car did mention that a mix of 93 would be a good safeguard against bad 91 gas and when it gets really hot. 7 gallons of 93 mixed with 91 remaining give me 92 octane. This is my extra safeguard against detonation in addition to
My goal was not to make the most power on crappy 91 octane but with either 100 octane or e85 if I get the itch for more power. I already have enough problems trying to keep the tires from spinning with the current power level (in 1st mostly but the quaife has helped make the most of the power).