duals vs. x-pipe

right now the truck has true duals, with pacesetter LT's, into old flowmasters, with 2.5" pipe. sounds very good, imo, even with the small, weak-loping cam:o

so, how much am i losing by not having an x-pipe, and just having straight duals?

i have heard the x-pipe sounds a lot better also.

truck is a 79, so no cats.

thanks