satisfactionII

I just ordered a new exhuast system for my 502 MPI. The parts are the Gil manifolds with Hardin Marine riser and tailpipes. I am also going to use the Hardin Marine Cyclone switchable mufflers. Will I need to reprogram the ECM?

deboatmon

Most do not require reprogramming for that mod. That is what I've been told by several qualified engine builders. I too have 502EFI's with aftermarket cast manifolds ( Stainless Marine ) and many other mods. Stainless Marine is my preference for this type set-up though. The riser-manifold joint allows for much more lattitude for installation alignment if you by chance are going through transom with your pipes. I'm guessing performance is about the same on either one. Not a significant change in mph. The only thing I've seen on the Gil is that the plugs are pretty hard to get to on the inside bank between two motors. Although there is not a significant change in mph, I strongly believe in this type of addition if only because of the elimination of the through joint water passage and the heavy, rusting steel. They do sound nice also.

madbouyz

When I upgraded to S/S exhaust and better breather it was recommended to install the 'vortec' fuel pressure adjuster to bump the fuel pressure up .
I got mine from Teague ...

JasonSmith

I'm in the process of adding Dana exhaust to my boat. Well, I've ordered it anyway... I am having the ecms done just to get the rev limiters bumped to 5400 RPM. I am also adding the fuel pressure regulators for a little bump.

satisfactionII

Thanks to all for the input. I was hoping that the engine would at least run after these small mods... know what I mean.
Thanks again.