I talked to Jim with Indy while I was at the Mopar Nats. Pointed out to him what the Hughes site was saying about the spring seat and that limiting HP. His response was that the seat could be cut .100 with no problems. 1.625 installed height plus the .100 cut is equal to .1725. Add + .50 retainers and you are at 1.775. Put a + .50 keeper in and you are now at 1.825 Installed height. Are my figures correct? These installed heights should produce the HP plus some that Indy says the heads will make. I know this is my first post on this site so that will make some people suspect my info. I would recommend you call Indy and verify this info with Jim. I have a circle track IMCA modified customer in N.C. whose cylinder head guy is very impressed with these heads. The heads were on display at the Nats and they look pretty good. When this info was posted on Hughes website it caused me to lose the sale of 4 sets my customers had on order. I am trying to dispel bad information here. A person could cut the stock valves to match the RHS/Indy seats put the heads together and everything is a go. ALMOST a true bolt on. I recently had a STOCK set of magnums worked for the class I race, for $600+ more I could have had heads that out of the box would make a bunch more HP. Before anyone starts dishing me call Indy and speak to Jim.
Thanx
Allen