Both really good companies. If you had to make a blanket statement IPD is probably a higher end, and certainly a much larger company. Frank/EST is more grassroots oriented, and offers a large range of products at very good prices.
FCP discountinued all discount codes as of yesterday. What they did was just lower their prices across the board. For what its worth here is a Carlisle code that should work, 8rnf9f
Call Brice at Alamo autosports. Hands down the best systems I have seen. Mention Volvospeed and he will get you a bit of a discount. Mike has seen his work.
Powdercoat will always cracked when used in applications like this, ie that flex. Stay on Don and he will usually come through. Be prepared to wait though. That said what in the world made you buy anything from Evolve?