How to find exhuast manifold leak?

[PHOENIX]

I was working on my truck last night (timing and idle speed) and noticed a slight exhuast leak sound coming from the passenger side manifold, efe valve, or maybe the collector area. I couldnt tell for sure. Right when I rev'ed it up you can here it for a split second. Whats a good way for finding the leak? I plan to do the exhuast on the truck soon (I have everything I need), but was holding off so I could get the headers coated. Im real short on cash right now and will be for awhile so I may just paint the headers and put everything on. Even if I do just through everything on, it might not be for another month, so I would like to find the leak.

Anyone know any tricks for finding exhuast leak?