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CMI and EMI exhaust for 502 vs 496

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Old 04-27-2006, 12:01 PM
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Default CMI and EMI exhaust for 502 vs 496

IF people are really seeing 2-4 mph gains with the CMI and EMI exhaust why don't the 502 Mags see the same gains? I know they claim hp and tq increases but it seems in the real world an exhaust only changes on the 502 mag gives little or no top speed gains.
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Old 04-27-2006, 12:47 PM
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Default Re: CMI and EMI exhaust for 502 vs 496

I have used both exhaust systems and have had very good luck. I have used the EMI Exhaust on a 454 mag and 454 mag mpi.

On the 454 Mag the increases were minimal (@2mph), until I made considerable engine modifications.

With the 454 Mag MPI, I included an ECU upgrade kit from Arizona speed and Marine. With some prop work (lab and 1 inch pitch increase), I saw a solid 4 mph gain on a Velocity 260. Still needed to run RPM @ 5200-5300.

Have had 3-4 MPH increase with CMI on 496 HO on a Velocity 290. Just received the Whipple reprogram back. Will be testing with that this weekend.

Last edited by Oh Deere; 04-27-2006 at 12:54 PM.
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Old 04-27-2006, 12:55 PM
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Default Re: CMI and EMI exhaust for 502 vs 496

Quote from 'Trailerboating' magazine: "Of all the modifications that we did to the 502 Pachanga over the 10 month period, the biggest single gain was Stainless Marine's exhaust. 225 rpm, 4.6 mph..........
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Old 04-27-2006, 01:12 PM
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Default Re: CMI and EMI exhaust for 502 vs 496

Quote:
Originally Posted by BROWNIE
Quote from 'Trailerboating' magazine: "Of all the modifications that we did to the 502 Pachanga over the 10 month period, the biggest single gain was Stainless Marine's exhaust. 225 rpm, 4.6 mph..........
Brownie, was that on a EFI motor?
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Old 04-27-2006, 03:28 PM
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Default Re: CMI and EMI exhaust for 502 vs 496

Sure did the trick on my 502's in a 38 Baja
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Old 04-27-2006, 05:28 PM
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Default Re: CMI and EMI exhaust for 502 vs 496

Quote:
Originally Posted by kr1276
Sure did the trick on my 502's in a 38 Baja
Can you elaborate a little? Did you do exhaust only? What exhaust did you use and what were your top-speed gains?

Thanks
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Old 04-27-2006, 06:02 PM
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Default Re: CMI and EMI exhaust for 502 vs 496

FYI, Saw a new IMCO on Ebay today...
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Old 04-28-2006, 12:05 AM
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Default Re: CMI and EMI exhaust for 502 vs 496

I put a set of Dana exhaust (only) on my twin 502's and saw between 2-3 mph gain. I did not expect to see that kind of gain so I was very happy! It looks and sounds alot better too!
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