I have a 45mag with 175 hours and looking to get a little more performance out of it. Would a single carb kit give me more than adding heads or the other way around. The motor is on a 15x44 gatortrax with the hunt deck and runs a solid 30-32 now.

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Of course any little addition to the motor will help, adding a carb will get you better throttle response, better idling, better fuel delivery, adding a head job will be all that much better, you'll see better bottom end as well as load carrying and some on the top end as well. Opening up the heads creating better air flow means more fuel delivery needed, the carb, a head job and exhaust all work hand in hand.

Lol he said-head job-

What type terrain are you running the most?
I added the carb and gained a little speed but much better throttle response and noticed a big difference when running in mud. The motor won't kill as easily when you dig it in and will run at lower rpms as to not blow the prop out. The mikuni is a little more sensitive it seems but that definitely doesn't outweight the gains.
Can't speak for heads yet but everyone I know is high on them.
Like Take'em said, to paraphrase...It's all good!

Im mostly running just marsh in the delecroix/canarvon area. Most loads I run are 3-4 people, pirouge and gear. I also shoot nutrias with this boat so caring a load is important

do a carb first and if that dont get you what you want , do some head work and then you'll get all that you want and more, those motors are semi built anyway so the addition of carb and heads will compliment it nicely and carry anything that you want, my buddy has the carb and exhaust and he can step 13 alligators in his boat and he loves it, we are gonna do his heads after the season and his carrying abilities will be endless

The SS valves are an advantage of doing the heads. I'm sure that will help my performance in itself.

Also wondering if the 32" outdrive would help things out?

I think mb puts shims on valve springs but I don't think they put valves on the 45 or 5000

The 5000 I had came with Manley valves, not Briggs.

45 MAG -This is from the BPS website.

- BPS Cam
- BPS Stroker Rod & Pistons
- Roller Rockers
- Stainless Exhaust Valves
- Custom 4500 RPM Governor Spring
- 6 month warrenty

So if my speeds are 30-32 now what can I expect with the single carb or heads or doin both

I am no expert, but after conversations with motor gurus this is how I understand it. If I am off base I am sure, in fact I am positive someone here will correct it.

Carb + Heads = more power through your RPM spectrum if you did both. You would see a few MPH top end gain, but the biggest improvement that you would see is the power under a load.

Carb = More response and faster response to throttling. May see a minimal gain on top end, but mostly see the gain in hole shot. No lag due to throttle spring assembly on stock carb.

Heads = Not sure that you would see the gain like you would with the combo together as the stock carb would be a choke point. The heads would allow for more fuel and air, but the carb wouldn't be able to get enough to it.

Had 6 hrs on it when I got it, & it was a 5000 then.

I didn't know Cody did ur heads, how'd it run afterwards

When I first got it, I ran 32-33, but the valves were leaking really bad & couldn't even break 28 anymore. After heads, I was back up to 35, so I gained about 2-3 over where it was originally.