CMI vs HP500 exhaust
 

What are the benefits of scrapping the stock HP500 exhaust and going with CMI?
Does anyone make a header style exhaust manifold that will mate up with my existing tail pipes and give an appreciable increase in flow?
At what point is the upgrade worth the expense?

Thanks
Shawn

Depending on the year HP500's you have, pre 99 or so had shorter risers that allowed for some water reversion. Merc later switched to the taller style riser that eliminated that problem.

The Gills have aluminum manifolds, and will have to be replaced at some point.

The CMI's will eliminate any reversion issues, allow more room to access and work on the plugs to change them, allow easy valve cover removal, and since they are stainless, they should just about last forever.

In addition, they will help scavange the cylinders better, thus increasing HP..... At some point you will have to replace atleast the Gill manifolds, so might as well go with the CMI's, plus they sound better.....not to mention look good !