Admittedly, I'm not overly concerned with resale. The price I paid for the boat was something that i was very satisfied with; and I plan on keeping it for a long enough time that the difference in depreciation is not something I'm considering.

What about something like headers/aftermarket manifolds? As far as I've seen, a kit can be purchased for ~$1500, and as a bolt-on, something that could be removed should I ever want to revert back. Would they offer much of a performance increase while maintaining the stock exhaust exit?

Out of curiosity, what did you do to your 6.2s?

on the Cobalt 220 BR - bravo III - do not remember about what prop changes I did but I did do some filing on the edges to sharpen them up on top of. Also did a lot of reshaping of the skeg and believe it or not that help as well. I could try to find some pics of the boat and send them to you if you like. The boat did handle very well & pretty fast for a family rec boat especially for a Cobalt.

IMO the placement of weight and some taken out really helped the boat. I think I gained 6 or 7 mph with props, running thru hull with silent choice, playing with weight, and messing with the lower unit skeg. No other mods nor to the engine were done. I was going to put aluminum exhaust on it to save even more weight but sold the boat beforehand. I remember the people who bought it were very surprised how fast and how fast the boat accelerated on the test drive.

http://www.offshoreonly.com/forums/d...d-project.html

There's more than you could ever want to know about building 6.2s

BUP thank you so much for the response -- I thought about taking a file to the edges of the prop just to knock the "dirt off" but I was afraid that I would screw something up-- old adage if aint' broke don't fix it! Regarding get tee up and go - I can't brag enough about the performance - Our son pulled me skiing 225 lbs and believe me I was up and running before I could blink - also the wake isn't much -- that extended running surface design really helps.

thanks again

3pointstar

Headers will not add any power or speed for a small block. Stock exhaust is not extensively limiting for SBC applications. If it were a big block you might see some gains.

Yes, that was done with my sons GPS- don't forget the 7.4 mpi is 310 hp and the 6.2 isn't that 300 hp? Also, I obsessive about cleaning the bottom of the boat - we store it on a lift and I've hit it with cleaner already twice this year

3pointstar

The Merc 6.2 L - 377 CID is 320 hp. The 383 CID is really a 6.3 L and is not the same motor. The 6.2L has a longer stroke and at times it has caused some piston failures over the years. longer stokes in the cylinder bore are harder on pistons. I am not saying that every 6.2 L has piston problems but there has been some from Merc / GM. I am sure if you do a search on the net or even up here maybe some might pull up or least maybe mentioned about some form of it. I have seen 2 cases of it in person in the past 10 or 12 years..The 6.2 does not even come close in sales to the common 5.7 L - 350 in marine apps.

The 350 HO MAG is 300 hp coming from the sterndrives and in the towboat series engine at one time it was 315 hp from Merc. FYI

The only difference between the 6.2 (377) and the 6.3(383) is one has a standard bore and the latter is .030" over. Both use stroker cranks. Longer stroke is only hard on the pistons if the rod is too short causing excess piston skirt side loads.

I would gather the piston problems are due to them being Hyperyou'llcrackit pistons with high ring lands.

Good or decent pistons/rods/crank there is no worry about rpm'ng them.

In my case, the cool fuel unit allowed minerals to get shot down the fuel rail causing a lean condition that blew a piston.