Guess I should introduce my self first. Been here for a while reading reading and reading this is my first post! Dstone from missouri running a 45 mag on a 1648 war eagle have a few questions taking my stock 45 mag putting im heads on it and the q exhaust what kind of hp gains should I be seeing? And would those changes make it what they call a hd 5000?

Heads and mikuni on a mag makes a stout motor. It will respond well to new parts very well since you already have pistons,rods,cam and rrockers

I have a 2012 MB 45mag. 2 seasons ago, the motor started to just not have the power any more.. It was struggling to put my 1852 on plane with a hunting load. There was a point in time where I had 3 guys and gear and was running 11mph. After that season I decided I had enough and bought aftermarket heads, the single Mikuni, and the Q exhaust. Also changed to a hammer prop instead of a big blade. I now jump on plane in no time and run around 28mph with the same load...I couldn't be happier with the way it turned out.. Basically a 55 BAMF now. I think the issue was my heads might have been leaking causing the motor to be weak... In my opinion, do the upgrades, you will be happy with the results.

Find someone to do your heads for you IMO. The IM heads are somewhat mass produced, you can get a much better job with cleaner ports if you go with somebody who does custom heads, and go ahead and do your intake as well....port match and knife blade

^X2

since you have all the internals, i would not have the heads milled much, keeping your compression down.