I'm looking at 2 different boats one has a 93' 150 evinrude that the guy says it runs great ( i want a test run to prove it) also he says it has "hyper trim" i'm not sure what that is? The other is a  91 Johnson GT 150. Rebuilt power head, new power tilt/trim, 4 blade SS prop. Again i am wanting a test run in both before a decision is made? And to check for cracks and other details? Is there anything else i am missing that i need to check on ?

Reliability wise, I would go with the GT150.  Performance wise the Evinrude will be a little better.  Hyper trim is just a fancy name OMC used when they went to a faster trim system in the early 90's.  

The old X-flow motors are some tough motors, they burn a little more gas but had no where near the issues the 60 degree motors.  

Even with a rebuilt powerhead, I would want to know particulars.  What all was done during the rebuild.  Was it bored and new pistons or just rings.  Just rings never worked in those motors for very long.

Be cautious of the GT, some were notorious for having major problems and needing new powerheads.

The 200's and 175's not the 150's

The 200's and 175's not the 150's

Your correct, my apologies. I had a friend that had a GT and had alot of trouble with it, it was in fact a 200. Have heard others with similar problems with the 200's.

I have owned 2 GT150's in the past and both were good to me.I ran 'em harder than I probably should have but both still ran fine when I sold them.The last Ranger I sold had a GT150 and I still see it on the lake every now and then and the guy hasnt had any issues with it yet........and he bought it from me 4 years ago.That GT150 is one of the more popular motors running around my home lake......lots of them still on the water.