Here is a picture of my Gil set-ups. Same set-up as the one pictured in your post:

First of all any cast aluminum exhaust manifold would be a great upgrade for your engine. We sell all popular performance manifolds like Gil / Hardin, IMCO, Stainless Marine and others. Gil marine has been in the exhaust industry for quite a while now and has been proven to be a performance manifold even my Mercury themselves. Gil exhaust was used on all popular HP500 model engines with great success. Gil manifolds incorporate individual internal runners for performance, powedercoated inside and out for durability, unique turbulator to help extend valve life by keeping condensation from entering the cylinder heads, and individual water ports to help prevent "hot spots" in the manifold. The kit you are looking at even includes a stainless steel riser and all install hardware needed for installation. Hope that helps, and let us know if we can help with anything else.

Thanks,
KEPP

I recommend the Dana exhaust

the results and gains of the large units are very similar to
CMI `s at half of the price