View Full Version : C.M.I vs. Imco Powerflow

08-02-2000, 08:22 AM
I have a 2000 7.4 L mercruiser sterndrive and I was wondering which header or manifold would give me the best performance. Custom marine headers or Imco powerflow manifolds. Which one would be louder? I like it loud!

08-18-2000, 08:52 AM
I beleive the CMI will be louder and flow better. Depending on what style you chose. The CMI keep the water and exhaust separated closer to the transom wich makes them louder.
This does come at almost twice the cost. :^}

08-20-2000, 01:14 AM
On the 7.4 L you will probably not be able to notice a significant difference in performance between the CMI headers and the Imco Powerflow manifolds. As "Baja" said, you definitely will notice a difference in the prices though! The CMI headers will be the louder of the two, much louder! If you decide to go the route of the exhaust manifolds, you may also want to take a hard look at the EMI(Eddie Marine) manifolds. They are even less expensive than the Imco's, and have better performance specs. Then you can spend the difference on some additional upgrades so your ride will not only be louder, but FASTER also!!!
Good Luck!

08-24-2000, 10:27 AM
I just installed the Stainless Marine exhaust. What's nice is that it come COMPLETE. Throttle, ECM, and oil filter bolt right onto the new brackets.
OH yeah it's LOUD!!!

09-06-2000, 06:45 PM
I have a 385hp 454mag and I just installed gil. Gil comes with all the bracket for the install, performs great and sounds good.
[This message has been edited by IBOATFAST (edited September 06, 2000).]