indmar EXT cat exhaust mani's-do they make a diff?

According to a boat dealer i was speaking with the EXT cat manifolds are now available on the 383...for 09 & only for Malibu..not MC 6L??? I was looking @ a 23lsv & comparing it to an xstar...
so apparently these manifolds significantly increase the efficiency of the engine..as much as I guess you can expect from a 400hp highoutput v8...
Who has them? what boat? engine size..and do you notice any difference in consumption...Fuel that is..not the beers your buddies drink while on your boat...haha
as well how hard you are running the engine
Just wondering as i search for a newer ride...what to narrow down the years and engine selections..if infact these EXT's are a key selling feature??
Any feedback you can offer is greatly appreciated

I have them on the 340 in my supra. They do cut down on exahust gases. Dont' know about fuel consumption. Unless your putting 400+ hours a year on your boat, fuel consumption shouldn't be that big of a deal if your buying a $50k+ boat. I wouldn't let it sway your decision.

same here, i have them on my monsoon in my vlx, absolutley no noticeable exhaust... a huge difference coming from a MC with a 8.1

same here, i have them on my monsoon in my vlx, absolutley no noticeable exhaust... a huge difference coming from a MC with a 8.1

I have them on a MC mcx (350) and you can tell they cut down on fumes or at least the strong fumes. They do save very small amounts of gas because you also get an O2 sensor after the catilactic converter. This allows the engine to fine tune air fuel mixtures. Without an O2 sensor the computer compensates and guesses the correct ratios but it can't check itself and correct. I would guess that you would have to own your boat for a very very long time to break even on fuel savings vs initial cost but I think it is worth it just for the lack of fumes.

Have it on my Supra. Ditto 1boarder_kevin's comments.

One thing that hapsn't been mentioned -- it's a lot quieter too. There is a noticeable difference from behind the boat between Indmar's Cat (340hp) and non-cat (315-hp) versions they offer in Supras.

Sulmaxwell- I will disagree with the malibu only having the EXT CAT on the 400 hp Indmar engines.

Supra has the ETX CAT on the 409hp 6.0L Here are the specs on the Supra 2009 Indmar 409

GM LS2 Engine Block
– Chevy Trailblazer SS
• Aluminum Block and Heads
• Stainless Steel (ETX CAT SS)
Exhaust
– 2 oxygen Sensors per Side.
• 10.9:1 Compression Ratio
– Premium Fuel
• 1.46:1 Trans Gear Ratio
– Improves out of hole
performance over initial 2008
mod

Mastercraft has the cats on the LY6. In 2007 the MCX and in 2009 the LY6. I had my doubts and concerns at first but now I'm on board with the cats.

The best thing is you dont smell like exhaust at the end of the day. I can tell a huge difference in the smell and no difference in performance.

I have an 09 23LSV with the HH 383 and it has the cats. Very quite compared to my buddies 06 malibu with the HH. My fuel economy is up quite a bit from my 06 vlx with the monsoon 340, I didn't expect that but I'll take it. Boat has a 55 gallon tank and I had it out friday, sat, and sun last weekend during the 4th surfing and wakeboarding, even pulled a tube for a few runs for some kids. Burned half a tank and put 12 hours on the boat.

As for exhaust smell I honestly can't tell a difference from my non-cat 06 to this boat.

(Message edited by 05mobiuslsv on July 11, 2009)

ETX CATS are available on MC 6.0L

Here is a picture of a 6L Salt Series w/CATS

Catalytic converters convert the colorless, odorless, tasteless, poisonous gas known as Carbon Monoxide (Co) into Carbon Dioxide (Co2). They also burn any unburned Hydrocarbons (Hc) using the remaining Oxygen (O2) left over from the initial combustion event. Ones nose is not the best way to detect an odorless gas.

The converters themselves will have no positive effect on the engine performance, as the just convert leftover gasses into less harmful and less polluting gasses that have already left the combustion chamber. The fact that these engines have a feedback ECM, will result in less fuel consumption without the loss of performance.

HEY! that's fantastic! thanks for the answer, I appreciate all the feedback...definately looks like it's a value added feature...that I'm going to be looking for!

so...
Here's the kicker....
what years did MC and Malibu start putting them on and which engines?

I think Malibu started in 2006 and I know Mastercraft started in 2007 with MCX

Malibu started in 2007.

huge difference.