I have a 86 Baja 320 with 400's The boat has a old shool stainless marine 3" tubular type exhaust, it is hard to access the front of the engines and plugs with these, I can get a setup of stock 88 BBC cast iron exhaust and it is 4" from a friend, would I actually gain anything at all from going from the 3" stainless front riser to the stock 4" cast iron stuff? it would make working on it easier and will prob sound better, the 3" give it a "cherry bomb" muffler sound and I hate it.

The openings on the cast iron manifolds are still small looking but they were on a 330HP Formula with 4" risers.

I have this pic of what I have now, I will try to get a better one, I have never seen an exhaust like this before!

if you get rid of the exhaust faster, you will definitely gain power. thats an odd looking exhaust manifold setup, looks like to many bends probably is hurting power a little.

A friend of mine had that exhaust in his 30' Carrera back in the early 90's....sure looks crude! I am not sure that by going to a stock Merc cast iron non-breathin' exhausts is going to make your time worth it enough for more HP. Find some used GIL's or Stainless Marine or other quality comparable aftermarket exhaust manifolds that breath much better than the Merc junk and what you have now. Otherwise, it would probably be safe to say that it is going to be a waste of your time.

I figure these were probably really cool back when they were made, not sure if they are hurting it or not, I would assume that with what engines are doing today as far as power these would suck, but I guess Stainless marine thought these were good back then, maybe they would be fine for the 400hp engines, I mainly want to get rid of them to make easier access to the front of the engines to work on, I am always playing with something!

I have to pull the engines in a week or so, I will post a pic of them off the engine, I want to see what they look like inside as compared to the stock cast iron stuff, only reason I may use stock cast is I can get them free.

Here is a better pic, got one removed tonight, what a pian to remove!!

Those cant be too good for decent exhaust flow!!!

If you have a standard bravo exhaust cut out. We can get you into Unitops for the same price or less than manifolds.

Let us know if we can help.

Kirk
Ateco Engine and Dyno Shop - Your CMI Source
(847)623-2737

I hear ya.....it just seems like going back to a stock Merc cast iron exhaust system would be taking a step backwards, but it would be truely hard to say unless you dyno tested both exhaust systems for comparison. I would think anything would be better than Merc's cast iron exhaust system, but what do I know?.... I only kill bugs for a living.

Nice looking boat you have there....assuming that is your boat in the avitar.

took one off to see how it looks on the inside, they actually are a truse full 3". I looked at my friends 4" stock merc stuff, the openings on them do not seem any bigger.

Thanks on the boat!