Ok, I got my stuff I ordered in yesterday. Headers; reducers; h-pipe kit; mufflers. I got under my truck and did some measuring this evening. From rear of mounting flange to tip of collector on header is 18". I have to run the left pipe over to the right side pretty quick off the header. I was thinking of putting a 90° bend off the reducer, and running pipe across where the "Y" pipe runs, or just behind the transmission- whichever I have to do. Then another 90° from there to run it parallel to the right side pipe. The h-pipe kit will go as close as possible to the 90° on the right side of the transmission, then short pipes to join the mufflers to the h-pipe (about 12" or so).
Does anyone have a better idea? This is the best I can figure out with the stock fuel tank in the way. The h-pipe is 12" on each side, the mufflers are 18" case length, 23.125" total length.

 

Here is a little diagram I drew in MS paint just now, if it helps. I need to know about how long to make the pipes.

 

Is there no way of going into a 45 degree angle? I think your drawing will push pressure back towards the engine.

 

Is there no way of going into a 45 degree angle? I think your drawing will push pressure back towards the engine. Also... because the of the 90 degrees angle, your right exhaust all of the sudden becomes a LOT longer.
The length of your exhaust determines for a great deal the amount of HP you get from your engine. Going into a 45 degree angle will shorten the total exhaust length for a great deal.

Of course, it is possible to go into a 90 degree angle. Most Nissans, toyota, ... do it.