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mybobtail
11-22-2013, 09:57 AM
Hi I have a 2013 prostar with the 5.7 I was at the boat ramp today and a guy comes up says does this model have the converters in .i go I don't know .he says well if they do get the dealer to take them out you notice better performance. Anyone got any comments on this.

JPK
11-22-2013, 02:31 PM
I don't think you will notice that much a of a difference. My buddy's '09, X14 had converters and it had a improved "header" to offset any power reduction. Most newer converter flow very well and the motor is tuned to run with converters. I think all the newer MC's have converters.

Did you know the guy or was he some random idiot making a statements that he couldn't support? Personally I would check with the dealer in the impact to your warranty for removing the converters on a new boat.

Aric'sX15
11-22-2013, 02:33 PM
If im not mistaken my 2010 didnt have cats in it, but they do rob you of a little power.

MattsCraft
11-22-2013, 02:54 PM
Pretty sure Cats were on '08 up, for sure '09.

I would think the engine is tuned for the Cats, removing would just cause problems, not sure how much performance improvement you would get. I wouldn't be removing them for sure.

Engine guru's please chime in...

1redTA
11-22-2013, 03:05 PM
I'd leave the cats in, you remove them and Id be afraid your engine would throw codes

CantRepeat
11-22-2013, 07:59 PM
07 MEFI5 and up motors have the CATs.

http://www.marineenginedigest.com/profiles/indmar/indmaretxcat.htm

snork
11-22-2013, 10:05 PM
not the LY6 wasn't till 08 and L18 never did

CantRepeat
11-22-2013, 10:42 PM
not the LY6 wasn't till 08 and L18 never did

I think you might be confused a bit.

http://www.wakeworld.com/MB/Discus/messages/65921/715166.jpg

snork
11-23-2013, 09:27 AM
That's a first for me :)
what year and model is that
I know of several 07 XStars with LY6 with no cats

CantRepeat
11-23-2013, 09:44 AM
Are they MEFI 4 or 5s?

snork
11-23-2013, 12:18 PM
what are the difference between the MEFI 4 or 5s in regards to cats?

93Prostar190
11-23-2013, 01:05 PM
Removing the CATS may may the dogs happy but ....... :)

My 2008 MCX has cats and O2 sensors on the CATs so if I removed them I would be taking away a pair of needed sensors from the ECM ... Also have you ever held one in your hand and looked at it? I doubt very much they restrict airflow as implemented on a marine engine ... Just my $0.02 opinion based on the exhaust manifolds and Cats that I have seen over the years.

FrankSchwab
11-23-2013, 01:47 PM
How often do you run at full throttle at high RPM?

If the answer is "seldom", then the only time you'll see any possible performance reduction is "seldom". Frankly, after forty years of exhaust cats, I have to assume they've got the technology down at this point and any impact is minimal.

The guy's experience with Cats was probably rooted in the 70's and 80's.

CantRepeat
11-23-2013, 04:42 PM
what are the difference between the MEFI 4 or 5s in regards to cats?

It is my understanding that MEFI 4s don't have the code or PIN outs for O2 sensors. MEFI 5s have the PIN outs and coding to use the heat and O2 sensors. At least that's how it is when it comes to Indmar and MEFIs.

The only reason I know this is I had to buy the ICAN adapter from DIACOM to work on a buddy's 07 that had CATS and a MEFI5. 06s were all MEFI4 with no CATs.

CantRepeat
11-23-2013, 04:44 PM
How often do you run at full throttle at high RPM?

If the answer is "seldom", then the only time you'll see any possible performance reduction is "seldom". Frankly, after forty years of exhaust cats, I have to assume they've got the technology down at this point and any impact is minimal.

The guy's experience with Cats was probably rooted in the 70's and 80's.

I agree. Nowadays the CATs seem pretty free flowing.

snork
11-23-2013, 08:39 PM
relatively free flowing the cats have a ceramic honeycomb about 1.5" thick if something gets lodged in there or pre honeycomb no mo free flow