I want to do this to my twim merc 200s but i am not sure what is the best way to do it. i got the housings from bob's and the directions said to drill like 8 1/4 holes then just bolt the housing on. after all this fill the spaces in with some marine tex to make them look smooth. i just saw an article today that showed one big hole and not a bunch of little ones but they also welded the housing on. has anyone ever had luck with this? any advice would be great let me know.

Hi Mike. I bolted em and welded em The only problem with bolting is the vibration wants to shake the bolts loose. I have seen them fall off. You would have to keep an eye on them, but you will not have to repaint as with with welding. I would drill one big hole 2.5 or3in make sure you drill all the way through the liner or it won't do any good.
Good luck
Michael

I always thought you were s'posed to yank the liners out.

Liners out and 1/2" diameter holes above the ventilation plate. Then if you wanted more, drill the big hole and put the Bob's relief over it.

I ran a "linerless" Merc with a 1 3/4" hole drilled in the center of both sides of the midsection. I made a flange with a 90 degree bend of 1 3/4" ID stainless tubing with a 7" straight length on it (one for each side). I cut the end of the straight sections in a slash cut and bolted them (with 3M 5200 too) to the midsections over the holes. They pipes were polished.

At idle, the pipes were underwater and the motor idled nicely (but sounded pretty cool). She howled like a mother on topend. The holes in the midsection jumped main jets 2 sizes and picked up close to 100rpm. The add-on pipes did not take anything away from the topend.

I may have some pix around here somewhere. It looked a lot cooler than it sounds..

I'd like to see those pics Mc , my friend and I are just planning on doing his 2.5 and want to do something dif..that sounds pretty cool...