Which is better exhaust upgrade for a stock 502Mag's for a TOp Gun? CMI or EMI or? will it make a difference to notice?

with stock motors,apart from the weight savings,i dont think you will notice the very small increase...maybe 5-10hp...go with the emi....a lot cheaper,and probly last longer...jmo

So EMI is direct replacement ? And it's cheaper to buy?but is it worth the expense as what wil I gain?)

if your present exhaust is in good condition,it's not worth it...keep the money to buy fuel and beer.....jmo

What they said. Do it if your current exhaust is shot, or if you have plans for some decent power upgrades in the near future. Go with something like the EMI, IMCO or KE manifolds and avoid leaky headers. If your motors are close side by side, you will have to pull the motors to do it, so once they are out, it's easy to work on them. If you are unsure of which problems you could run into, I'd suggest you contact the manufacture and ask what is involved in your particular case.

Good luck with it.

I'd say look arounf for some decent Stainless Marine take offs which should handle most engine upgrades you might do down the road.

So Stainless marine or how about imco or Hardin for that matter? Some people say for stock engine any of those should be about the same?
Thnx in advance