CAP071

My stock 502 mag/mpi exhaust is leaking. Any ideas on what I should replace the manifolds with? EMI? IMCO? Not looking to spend thousands on CMI. Motor is 100% stock. Would like a direct replacement if it is out there with no mods needed?

Thanks in advance.

obnoxus

I put GIL on mine when it was new, pretty simple install. I also have the stock original manifolds and risers that only have about 40 hours on them. Make me an offer !!!!!

Ric232

I installed Gil's on my 454 Mag MPI as well. There are minor mods required with most of the aftermarket systems, such as relocation of the remote oil filter.

If your exhaust is leaking at the joint between the manifold and riser, you would be better off just replacing the gaskets. And do it soon before it destroys your motor.

CAP071

Seems to be (pissing) out the the plastic tube where it goes into the manifolds. right where the blue drain plugs are. was told just JB weld around it for now?

CAP071

gil wet offshore?

Ric232

Cap,

Sounds like the plastic fitting may be cracked. I would just replace that part and make sure you install the new one with thread sealer. I would not bother with new manifolds.

seabeach

The fitting on my mailfolds broke this spring, and I replaced it. The biggest problem I had was the rust in the threads.
/Torbjorn

Vinny P

As everyone has said above, you can simply replce the plastic fitting or even just seal it up. But if you wanted to upgrade I would recommend Gil Wet Offshore Manifolds and risers. I have them on my motor. Personnaly, I like the idea of not having any water going through the riser gaskets anymore. But, don't expect any big performance gains. Maybe 200 r.p.m.

powerguy

CAP071

I just installed new set of EMI exhaust with the stainless riser for silent choice. It was not the easiest install to do and clearly not just a direct replacement. I had to cut 1" from the engine side of the silent choice Y diverter and 2 inches from the transom side of the silent choice y diverter to get them to fit correctly. I also had to "modify" the water exit on the riser to create a space for the water to exit the riser and enter the y diverter pipe. Without my modification the water had nowhere to go because the thickness of the y pipe blocked the 1/8" gap of the water exit on the stainless riser. I also relocated the oil filter to the transom.

After all that the motor sounds better and has more torque at lower rpm that allows me to get on plane faster and with less tabs.

I have done a couple of top end runs and estimate that I have increased rpm's by 200 to 300 and speed by about 1- 2 mph on gps. Will know final gains when I do a run at 1/4 tank.

Ric232

Everyone talks about 200 - 300 rpm gain with an exhaust swap not being much of a gain. That's actually a pretty big gain. Consider yourselves fortunate. (I'll whine one more time)... I got nothing with my GIL's.

Personally, I think some guys get "exhaust goggles" with they drop $2,000+ on motor upgrades and get no improvement. No one wants to admit it. That's why you hear a lot of "I had big gains in mid-range performance." It's a lot more subjective.