I have stock 502s with the original exhaust,,was thinking of replacing exhaust with GLM aluminum manifolds and risers,,
has anybody have any experience with GLM,,good,bad?

Thanks

average to decent for the money - only gain is loss of weight in which can always be a positive thing.. Most people that I sell them to are smallblock owners 5.0 and 5.7, as Big block owners really do not look for GLM to be the manifold / riser of choice especially 502 HO MAG apps. For big blocks I would pass on them and look into something to offer better performance gains.

IMO a good choice on the cheap and to drop some weight for a OEM stock 454 non HO MAG 300 hp carb or the 310 hp MPI engine.

I just got Stainless Marine ones yesterday in the mail as a matter of fact! I am very new to boating I might add and my OE manifolds were leaking externally at the riser joint (I haven't taken the old ones off yet but who knows maybe leaking internally also?) Anyways, I did a lot of research and I initially looked at those GLM manifolds as well but heard a lot of mixed reviews. After doing some research I wanted manifolds that eliminate the riser joint water passages completely since I am now very nervous about them after all the horror stories about leaking joints and reversion I have read. My next choice was the EMI manifolds which aren't too bad of a price and people seem to have good luck with them too. Then it was on to the Danas but after reading about them going out of business or reorganizing, or bought out etc. it was enough of a red flag for me to keep shopping since future parts availability may be a concern should there be a problem with them. After even more research I couldn't seem to find one negative thing on the Stainless Marine manifolds. Granted they were WAAAAY over the budget I was originally planning on which I am not too thrilled about, but If everyone is correct I will never have to worry about them again. Peace of mind is priceless I guess! I got a good deal on them too PM me for the info if you want.

When I got my Checkmate with a 454 mag the manifolds were very rusty so I replace them with the GLM's. I thought they worked great and excellent performance but the boat had Fastglass stainless performance risers on it and I believe that was the big difference. Fastglass isn't made anymore but if you can get a performance stainless riser that fits the Merc pattern that would be a decent way to go as well. I'm not sure any one is making one like that anymore.

I think CP has "super sport" options I was looking at too: http://www.cpperformance.com/c-1862-...ock-chevy.aspx

The fancy risers that fit stock exhausts are 800 bucks a set. They are pretty. But flow no better than stock manifolds with stock risers. The 800 will buy a whole decent used set of 496 manifolds and risers.