I Have a set of EMI thunders i just bought like 5 hours on them. I bought these before i realized i was gonna buy new motor and all. So now i have 500hp that i just refreshed and i gonna get heads and some other stuff to get 600hp out of the motor.

So my question is would it be worth it to buy the etop cmi headers or should i just use the emi?

bump anyone

The emi's will be ok to 600hp. Not as good as CMI's, but I would use them.

ok thanks

I ran the EMI's on 800HP blower motors for 2 seasons till I got my CMI Etops made, noticed no difference in performance of the boat when I swapped them out.

Thanks Back4More - you just saved me a ton of money!

It is not the HP as much as the cam spec that determines what you can do with that exhaust. You should call rmbuilder here on OSO. He would be able to tell you if that works.

Also, it usually takes either a cam swap or a severe increase in rpm range to get a full 100hp out of just a head swap when you are starting from 500hp to start with. If you were talking about a 500HP merc engine, you are sctually starting with 470hp from the get go.

Good luck with your project.

I ran emi thunders on my 625plus hp big block right up until this fall with short risers and had no problem,i just sold them because i got a smoking deal on some cmis,but i would run them again if needed,the only thing i did was always idled the engine at 1000rpm in and out of gear.

People talk like the IMCO and EMI manifolds are not that good but I am running IMCO manifolds on my Procharged 502 with mufflers and all of the engine accessories and it is making 850 HP and 845 foot pounds of torque.

http://www.donzi.net/forums/showthread.php?t=55279

There is nothing wrong with the manifolds and they will let you make good power, I am only suggesting that you make sure they are compatible with your cam selsection. You may just have to make a few adjustments to ensure none of the big R