'99 Velocity 320 with T-7.4 MPI. How do I know what to look for in headers? Would these work? For example?
http://cgi.ebay.com/ebaymotors/Rewar...QQcmdZViewItem

First off, headers are not going to make much difference on a 7.4 motor.
Second, Rewarder makes water injected, as opposed to water jacketed headers. You might want to check which these are before you buy. Water injected are only for open engine compartments.

Essentially, you are going to need a header setup for a stern drive application. There are a lot of brands out there. Going with stainless marine is always a good call. Your performance increases will probably be due to the wight loss more than any real HP improvements. Don't expect to spend less than 1000 for anything other than stock replacement stuff.

Rene

NO,jet boat headers,

If your looking at price look at some of the alum aftermarket manifolds