VR1

Has anyone put an aftermarket exhaust on a 496HO? I have heard that the stock manifolds flow pretty well. I wonder if a set of CMI's would "wake up" the motor like I have experienced with other FI vehicles.

HARRY

I installed a set of Lightnings and picked up 4 mph and 300 rpm's. I haven't checked lately but when I did this early last year no one was willing to sell me a set for that motor so I bought used ones and there was some fabricating involved (oil filter housing, shifter bracket, water temp sensors in the manifolds etc.) but it was worth it.

Mike Shaak

In some of the magazines that I get, I've seen pics of this engine with headers on them, so someone must be selling something that fits.

BHOCKETT

I e-mailed CMI and they told me to keep looking for there ad in the magazine's.
They currently don't make a set for the 496HO with Silent Choice.
Have you found any other performance products for your 496 ?
Also e-mailed ASM on re-tuning the CPU, said no dice on the Merc. computer .
I'm going to send out my prop to get the lab finish and hope to get into the upper 70mph range, best to date 73mph on GPS out of my 2001 Checkmate ZT240 496HO MAG, 25 Mirage plus @ 4800rpm.

HARRY

Spoke with Jim Wilkes of Wilkes Marine the other day and he said the powers that be (?) are finishing up an adjustable ECM that will replace the Motorola computer currently used by Mercruiser. He said to expect to hear more about it soon...