Your not supposed to use a two part powder coat with clear coat otherwise the clear coat will turn yellow over time from engine heat. Thats why it pays to take it to somebody who specializes in powder coating show cars ect. They already know what works and what doesn't work and how to properly prep everything.
Since I had mine PC'ed I've had to take the plenum off to replace an alternator and another time to replace a starter. There was no cracking or flaking off around any of the holes. If you want the best most indistructable finish possible for your pride and joy powder coating is the only way to go. I just don't know why anyone would go through all the painstaking process of removing all the top end stuff prep prime and paint it when it's going to only last 4-5 years before it starts flaking off. Even Sanjay had to take his 415 to Coreys and have the whole top end re finished because the LPE paint started flaking off. "I'm just saying!"
John is the freakin man at Precision Powder Coating.
http://precisionpowder.net/