I am running a 496 HO with CMI Sport Tube headers... I had them installed early summer. I am running a Bravo SS 24 P Prop. RPM when trimmed just right is running at 5000 RPM. I didnt notice a big difference in power ... maybe 1-2 MPH if conditions are just right. My question is, should I change my prop to a 26 or 28 P...

Any feed back please...

If you are bouncing on the rev limiter then I would jump up to a 26p but if your not you should just stay with the 24p. If I remember correctly, the 496HO rev limiter is set at 5150 which means your probably not touching the rev limiter yet. The headers only net about 50 more hp.

I didn't see any improvement with CMIs on my old 496 in my Donzi. I wanted to think there was a little but there was nothing. I finally yanked the 496 in favor of an HP525EFI.

kevnmcd, I dont think im on the rev limiter yet...

third childhood, I have been thinking about doing the same... Stepping up to the 525 EFI .... What did the upgrade to the 525 run you??? And who did the work...

Now that you have the 525 are you satisfied with the results???

Absolutely the best thing I've done to my boat. I purchased it new and would have popped for the 525 but Donzi only offered up to the 496 HO. It would run 73 and was a lot of fun but just wasn't enough to get into the thrill zone. The 525 gave me a solid 10 mph increase along with exhilarating acceleration and dependability. It wasn't cheap however. I paid $20,000 for a low hour take out from this site. I installed it myself but had to have my mechanic relocate the exhaust and install new tails that let me keep the Q&Q. That was over $3,000. Then the Bravo 1X blew after 7 hours so on went an XR upper & Imco shorty. Chalk up another $7,000. The Zeiger full steering was almost $4,000 and the BBlades Bravo 1 30p was about $700. I still don't have all the gauges working but the boat is dialed in and a blast to drive at a solid 83 mph, best recorded of 85.8 and bumping the limiter. The CMI Sporttubes were almost $4,000 wasted.

I already have an XR Drive,Dual Ram Stearing with Cable assist. I was originaly going to add a whipple to the 496 but after some research I opted against it... I just had the exhaust upgraded with the CMI Sport Tube headers... I agree with you that it was a waste of money... Now with the seasons coming to an end... I am thinking about upgrading to a 525... I found a rebuild that Mercury is offering a 1 year manu warranty for 25 K... I dont know what I can get for the 496 HO with the headers and roller rockers... I will have to do some additional research...

No, you want to prop that motor for 5K.

+1

Yup. Should be bumping the limiter in ideal conditions. 5,000 RPM in normal conditions.

just my opinion,but for 25K,you can get that 496 rebuilt with better rods and pistons,add a whipple and get an easy 600hp,with quite a bit of money left for gas and beer...that's what i did,and im happy with the results...jmo