Compounds would be nice. But I put too many miles on my truck to dump that kind of money into it. The amount of power they can get out of the 15, will determine if a get a 15 f450 next year.I'm actually leaning towards the 65/68 for quicker spool up. It should get me to my 600+ goal. If I build the motor later on I can do compounds or a single 73 or something