I just upgraded from stock exhaust with Y pipe and out the drive to Imco Powerflows and through transom exhaust. My 7.4 is mostly stock except for a larger Holley carb and K&N filter.
When I asked some of the local shops, they all suggested starting with upgrading the exhaust. I have to say that I am dissappointed with the result as the cost was about $4k.
Anyone else have similar results?
Part II:
The motor was recently apart due to overheating. Heads were sent out for a valve job. After idleing through a long no-wake zone the boat really hesitated once I hit the throttle. It seems like it "loaded-up". I have also noticed a lot of black "soot???" on the transom. I expected that there would be more due to the through transom exhaust, but not this much. Any suggestions?
I thinking timing may need to be advanced a bit.
Thanks