I have a 2004 heat with a 496ho. I was wondering what kind of speed I will get out of it with some cmi headers. I also have a complete 500 efi that I have been thinking of putting in the boat. What do you guys think would the 500 efi smoke the 496 with cmis on it. I need some advise I cant decide weather to sell the 496 or sell the 500 efi.
Thanks John

Don't let the numbers mislead you. The 500 EFI is a much stronger engine than the 496. Based on what others have claimed you will probably pick up 2 maybe 3 MPH from the CMIs. The 500 will be 2-3 MPH faster than that. What GPS speeds are you getting now? You also should consider a 1" drive spacer. That will give you several MPH and much better cruise.

I agree with bobl

The CMI exhaust is the best upgrade / perfect combination for the 496 HO but a real blue 500 EFI will outrun them.

Only negative side on the 500 EFI; you won't have the closed cooling system anymore

496 HO with CMI's ; Sound is AWESOME.... midrange "punch" and acceleration better all the way

Our 28 Heats CB/ 496 HO with "std" exhaust system are all turning B1 24P or 26 labfinished props

With CMI's we are turning 26 @ + 5100 RPM sometimes hitting rev limiter .... (on salt water / light load / 1/4 fuel) 28 Labfinished @ 5050-5100 RPM => PERFECT

Still no GPS in this boat .... (LIVORSI) Speedo showing 77-78 MPH

If future mods are in your plans, you're obviously better off with the Gen 6 502. You've got forged internals (vs cast in your 496), and more aftermarket mods/parts for the 502. Plus, the blue motors are blinged out, and let's face it, the stock 496s aren't the prettiest motors Mercury ever built.
Regards,
Steve

I think im going to put the 500 efi in. I go back and forth every day on what to do. The biggest problem I have had is how to get the water jacketed exhaust out of the headers and to the tips which are on the outter corners of the transom.

The 500 efi is in. everything is done except for the headers and exhaust. Waiting on cmi to finish the tailpipes. I cant wait to fire it up. Im also ordering a 1" drive spacer. I Have been tring to find the weight of the 496ho and the 500 efi. That 496 is a heavy *****, the 500 must weigh a lot less.

John,
I think you will be happy with the 500. It's a very reliable, fast, pretty, turn key motor. Lot's of aftermarket goodies available for modifications if you get in the mood for more.
I'm sure you've read about the 1" drive spacer many of us are running. The factory X dimension (19 1/4") is so high on the 2000 and newer Heats, the slip % is terrible in the midrange, and not much better at WOT.
Let us know what your before and after #s are. What kind of prop are you running?
Regards,
Steve

Thanks ive got a new 28 bravo 1 lab finished from throttle up. The boat had a 26 bravo 1 with the 496ho when I bought it. Im going to try both.

Started it today for the first time sounds great cant wait to see how fast she is going to do.

John,
Congrats on the swap. Sounds like it's going to be a fun summer. Let us know how she runs.
Regards,
Steve