That's not a bad idea. I'm not exactly sure why, but not very many suby owners talk about headers (in comparison to other enthusiasts). If you don't mind the difference in sound, equal length is the way to go. It's been proven to outperform unequal length in many respects. I searched, read and read some more about headers for months, and I've concluded that the best headers for the money are the gruppe-s equal length, GT spec gen III, and synic. Since you already have a twinscroll oil pain I would get one of the first two I mentioned. The GT specs can be purchased at iagperformance.com. They have the best price (trust me, I looked) and should have gotten a new shipment in yesterday.
If you are a fanboi that would die without the "boxer rumble," I would recommend cusco headers. Unfortunately, they are expensive. If you can't afford them, any other unequal header will do. Almost ALL of them have the same 4-1 design (GT spec gen II, gruppe-s unequal, etc.). Gruppe-s' are pretty cheap and they have a good rep, so I'd get those.
Btw, I'm selling unequal length headers that are replicas of the GT spec gen II for $250+shipping. The brand is xxtuning and the quality is top notch. Let me know if you're interested. Selling them ### I got cusco's.