4" Exhaust Hurt Performance?

[F-SUPER DUTY]

Just finished install,Cut Y and welded into 4" straight pipe to 36" magnaflow straight-thru muffler,2-45 degree elbows and out the side in front of wheels.Test drove truck and it seems to have lost little low-end power.This seems odd!From what ive read more is better.Do i need restriction?Any help would be welcome.Truck is an 89' superduty dump,7.3 IDI non-turbo,E4OD,5.33 rear,weighs 9000 lbs empty.

 

[Whit]

the less resistence the better

must be yer imagination

 

[Pipeliner_86]

I have an extremely open exhaust system, and I dont believe I have lost any performance. I had stock exhaust before, and with my open system I run now, the truck probably runs out a little better, but it wasn't a night and day differance. What you might be experiancing is the " it's louder now, so it should feel faster " syndrome. I know I have come down with that before.