Imco exhaust and thats it. Had a hard time last summer pulling the rpm's though. I need to check my timing. I think it may be off now. Probably some timing chain stretch. Haven't checked it in a couple years. Either that or my valve springs are finally going away. The motor is 16 years old so it may be getting due.
Cool. I need to get the 454Mag modeled in DeskTop Dyno. The I could use that power data with the speeds we've seen to calibrate a drag curve. Your boat is the second data point I've been waiting for!