im looking at trading my boat single 454 mag (385hp) 28zx donzi in for a twin 502 mag (405hp) 33zx donzi. I know the 454 was a good motor no issues and forged. Is the 502 just like the 454? it has around 430hrs on it, and i would like to make sure the motor can be ran wide open all the time like i did with my 454. Anything with the 502 i should look out for? Thanks

Only difference is bigger bore. Its not just a bored out 454, the walls are bigger around.

The 502's, if MPIs are 415HP. Take a good look at where the riser/manifold meet. If you see rust on the outside, it's probably time for exhaust.

Both known to be good boats.. Both the 454 & 502 have been around a long time & have been known to be good units. Obviously some models were more sought after than others & performed better too. But there was usually a price tag as always to get into the higher performing ones.. Jamie / Lakeside