Thanks for the info. How was it mounting the shifter bracket and ECM with the IMCO exhaust? Pretty clean install? Pics would be great if you happen to get a chance.

400 lbs is more than I would expect. Each stock manifold is 100 lbs heavier than an IMCO? Thanks again.

I weighed them when I came home a stock manifold and riser is 76 lbs.The Imco manifold is like 10-15 they are very light so its more like 250 lbs but at the very rear of the boat that is still a lot.
You can get (you need) brackets from Imco they are different for shifter and ICM.The bolt to the riser studs.The ones I got tilted out to much but if you bend the before its real hard to get the rear riser bolt its tight.So I just covered the riser in a thick rag and bent them toward it with a big pair of channelocks after they were bolted on.If you don't the shifter and ICM bracket will not clear the valve covers.I did have to re drill one of the holes for the ICM and you only use two bolts for the shifter.And the manifold bolts that Imco sends are a little two long especially on the first and last port.Use the old ones on them and double washer the rest even though the seemed fine.

I tried to post pictures but they are to big will shrink them latter but I have a lot to do tonight if you want PM me your email and I will send them to you

You're right, 250 lbs is still a lot of weight and that swap takes it off the right place. I imagine rough water handling may improve a bit. I know my 292 feels a bit tail heavy in the rough. PM sent, thanks.