True regarding the direction change. I'd recommend X pipe or single exhaust on a stock Vortec mostly because of application. There's only 196° of duration on the cam and with a stock converter. The scavenging will help you get some of that grunt back.
Exhaust pipe size can also play a role...But I'm assuming you're running less than 2.5" diameter pipes.
Minus all the science stuff, if it was me, I'd put an X pipe on. Took me a few years to figure out...Hey, race car stuff isn't optimal for everything. Especially a daily that you have some concern for economy or particular function. I'm not saying it'll be a tire-fryer all of the sudden, or you'll be able to yank a 12,000 pound trailer without noticing...But for the cost, it'll give you some of that torque you're looking for and who knows, maybe a half mile to the gallon while you're at it!