did anyone pick up any mph over stock....???

When I put Danas on my 454 Mags, I gained 2 mph & lost 100 lbs. over the stock setup.
I can't say that that gain was all the Danas, I put on some roller rocker arms at the same time. Not that roller rockers would make that much of a difference, but I'm sure it helped a little.

I have been having the EMI's for 5 years with no problems. I got the long risers, they sound great! You will lose a lot of weight over the stock cast ones

I wouldn’t, there are a lot of other products out there that would last longer and perform better. I have used them and only lasted 10 hours.

I installed (2)sets of Stainless Marine manifolds on my twin 502 MPI's. Nice quality, kit complete, 5 year warranty, and dry joint design. Brownie provided good support @Stainless Marine on any questions. it was nice clean install with all correct brackets included for the MPI. Cheaper systems on market, but I thought Stainless Marine was the best value. I wouldn't hesitate putting them on another boat.

When I do change exhaust, is a fuel correction nessisary? 2000 502 mags," leaning towards CMI"

As a general rule, no. If you get soot on your transom, you should have enough fuel for the new exhaust. I had no problem when I went to the Danae on my 454 mag mpis.

I have EMI on my merc 502/4 years/ no problems. Lot less weight than stock. As far as picking up mph.........not really sure...maybe a few. I'd go with CMI's just because a nice, shiny, full header system looks sweet.

I've had EMI's on my 454 Mag Mpi for 8 years. They are still working and look decent. I saved 64 lbs and picked up about 2 mph. I played around with an adjustable fuel pressure regulator and ended up using the stock pressure setting for best performance.

Go straight trough with them, dont use them with silent choice if you have lots of Horse Power.

We have sold several and the customers lover them