OEM manifolds. This wideband thing is new to me for boats, and looks like the best route to go. I absolutely hate jetting a carb the old school way.;). Wags looks like they've got a cool spacer.
http://i622.photobucket.com/albums/t...132B16D485.png

And Innovate looks like they have a good kit.
http://i622.photobucket.com/albums/t...14A38C8B00.png

I have no idea. Where do I look for that?

OK, as you never ran the boat before, maybe the boat is the issue ?? could be very wet and heavy ? also those are not performance hulls to speak off...could have excessive hook in the bottom ?

I used the wags spacer for the closed joint 496 style exhaust and it works perfectly..... I bought the AEM brand wide band kit and it looks exactly like the innovate and it works great...... Makes tuning the carb a breeze plus gives you instant tuning info so you can see if you are leaning out........ FWIW, the stock style log exhaust is horrible for performance..... The 496 dry joint is much better and I would recommended changing them..... You can find new ones for a good price. I found a set of used fresh water aluminum that we're in excellent shape and so far so good....... Do you have an aftermarket cam and heads?

GMZZ502 cam Edelbrock performer oval heads, so yea the exhaust manifolds are a weak link in performance in this setup.

Aluminum like these?

http://m.ebay.com/itm/310750221213?cmd=VIDESC

tpabayflyer I have a few dumb questions, do you need two spacers and do you run them all the time or do you just install during testing? does the kit come with extended bolts and gaskets?
thanks

Checked the electric fuel pump pressure at the carb with 4.5psi at idle and it would drop when I burped it. It was only on the muffs in the driveway so I took it easy and held it at 2k rpm where it was struggling to hold 3psi.

The mechanical pump is bolted on and I just need one flare fitting before giving it a try tomorrow.

Looks like you found the problem.... I would say 6psi min...... I have 2 spacers but I am currently using one O2 sensor on the starboard side...... I have to use an extra couple gaskets as I am using the turbulator on top of the the spacer...... It's works great!!

That's all very useful and helpful info. Just curious if you run the gauge all the time, and how often do you make jetting adjustments?

I have about 15 hours run time on my 502 and the gauge has worked fine..... I have not made any jetting changes yet as my baseline jets were pretty much spot on! I copied a setup from another 600HP motor using the air gap intake and its a little rich on the top end but I am OK with that..... When the temps drop down this winter I may rejet as the cold, dense air will probably lean out my tune but I have the wideband there to tell me when to do it!!

And yes I have been running the gauge all the time...... Cars run O2 sensors all the time and they last for years so I think it should be ok....... As long as you don't get the O2 sensor wet from reversion.. Get some good exhaust on that thing at let it rip!