SB

iTrader: (1)

I'm giving you size info because I know it. Not telling you what to do. I have not tested the difference in real life.

The small boats I've done say 330hp and up get exhaust. Just because. And I don't consider it a waist on those because the person typically wanting to do as much as they could. We'll call it medium budget vs low budget.

SB

iTrader: (1)

I wrote the connecting flange on the transom is the same size. I pushed a 2" rubber cap over that too.

Anyway,
With better exhaust manifolds the other benefits other than weight are:

Spark plugs and etc way easier to get at.
Starter - like simple !
Also, getting rid of y pipe adds even more room to access everything back there. I'm in a lot of engine compartments and this is worth it's weight in gold. Sucks to work on things with Y pipe and fact exh manifolds.

Gannz

As usual with something like this, the budget was blown a long time ago. LOL

I can always change the exit later if necessary. Need to get the 383 built first and if I'm not happy with the seat dyno or the numbers I'll go thru the hull.

I would like to go all aluminum with individual runners or aluminum/stainless even if I don't go thru the hull. If it doesn't help flow, I'll still lose 100 lbs off the stern. Would the GLM all aluminum setup be sufficient or would I need to step up to an aluminum manifold and stainless riser?

Gannz

Sorry, was typing that other reply and didn't see this one until after.

I'd probably opt to keep the Y. I hear ya on the room but mine's pretty roomy (under a full sundeck). I like wrenching my own stuff but I do hate it in tight spots. The reason I'd like to keep the Y is if I wanted to run a diverter in the future. I remember reading one post where someone tried all different kinds of exhausts and exits and liked a diverter (not switchable, just an open diverter) the best. Said it gave the best sound and still flowed well at higher RPMs.

SB

iTrader: (1)

.
.

SB

iTrader: (1)

.
.

Gannz

I hear ya. My checkbook doesn't though. :-(

I'm hoping to get out for $1500 and I'm confident I can do it for 2k (exhaust not included). Let's call it $1750. Those CMI headers are $3500 not including hoses, diverters and/or silencers, and tips. That's a 300% price increase for a 6% increase in performance. LOL I'd love to have some stainless headers but the pricing on em is just over the top IMO.

I can swing a lightly used aluminum set. Maybe an aluminum manifold and stainless riser if I can find a really good deal.

87MagnumII

I ran that cam for a few years on stock merc exhaust with no issues.

veloc410

Only reason you need thru prop is to stay quite around the docks. Plug off the gimble housing and outdrives. Home Depot 2.5 inch rubber pipe cap and a little grease.