I think this is a "do what makes the most sense for you" scenario. If you are only driving this on the street...can you feel the approximate 20 top end HP that shorty headers may gain vs manifolds? The engine will certainly breath better, but at the same time, if that takes you a weekend, and several hundred bucks in getting exhaust re-done...then thats your call. I'd make the same contemplation if it was worth the time and money. Now if we're talking manifolds to long tubes...yes I 100% believe THAT would be worth it. If you see any strip action, assuming you hook...I'd guess manifolds to long tubes may gain you a few tenths. manifolds to shorties...probably 1/2 of that gain, but also depends on how much the manifolds are choking it. I have never "bothered" putting shorties on anything in my life, and probably never would unless they were cheaper than a replacement manifold, and i had a cracked one or something. if you're going to the trouble to install headers, i'd go long tubes. Now if those are those TTI Tri-Y things...those are closer to a long tube than a shorty...so if you have them, i'd probably throw them on.
Kinda rambled above, but I hope it helps.
