George the Preds are used by many in five western states for three pole AMA 424 APRA racing typically they will reach 125 mph using almost universally TT .40 Pro with muffler per rules and proped for around 16500 with a mandatory APC 9x6. I suspect even piped with your engine it will be somewhat slower. The lack of CF under the skins is not an issue and not needed in 424. Its with Nelson and Jetts in 428 where they do go around thirty miles faster that it does become an issue.

Check around and find out what racing may be near and why not build to local rules to give racing a go, but I must warn you it is infectious.

John