Good info. I love seeing real numbers...which sometimes can be eye opening. People always assume LS stuff is SO much lighter than BBC stuff...and that is sometimes the case and sometimes not.

Yeah, I mean even a 300lb weight savings is pretty substantial. I think it will be even more noticeable in a multi motor application. I would love to see someone with a 283 Checkmate or 29 Fountain that has twin 454's do the LS swap just to see the weight/handling difference with the same power level.

Yes, a P29 would probably be awesome as the boat was built for small blocks to begin with and was pretty fast with it's stock 320hp Merc small blocks.

Some of the smaller singlle engine sport boats can lose 3-4 mph per person added. Also gain a 3-4mph for every 20-30hp added. Win, win with the LS.

The weight loss mph help comes into play when a few hundred pounds added or subtracted makes the speedo move + or - .

I weighed a set of factory small block cast iron manifolds and risers and weighed the Eddie Marine system going on. 88lb weight loss. Great for that boat as it was one of those that lost a few mph per person added.

My boat is one of those boats. The difference in the way my boat jumps on plane and runs out when its just me in it compared to when I have four people is about 7-8 mph. So the weight loss should help me out a lot there. Adding almost 300hp isn't gonna hurt either, LOL.

Are you going to add mufflers to the dry exhaust?

I'm going to run it and see how it is first. I have a feeling it's going to get annoying so I am looking into getting a set of clamp on mufflers. Right now I'm leaning towards the Drew Marine Shotgun's.

Any updates?

Just curious, what LS engines are real options that are available to the public?

http://www.gmmarinepower.com/products.html

andthen:

http://www.gmmarinepower.com/partners.html

Well, I got the headers back... FINALLY!! Got it fired up and it's still sucking water in. The modification added 15" of pipe to the collector and didn't mix the water till 1/2" from the end of the tip, and it was still reverting. So needless to say, the tails are going 100% dry. No water in the exhaust stream at all. But no way will I send them back to lightning as I don't want to wait another 6 weeks for him to do a 2 week job. I'm hoping to have them back this weekend.

Here is a slow-mo video my buddy took that shows it reverting. This is with the exhaust dry to the tip. Don't mind the blue tape everywhere. I was doing some transom touch up after I cut it to fit the new exhaust.

https://www.youtube.com/watch?v=imt0LJROxtY