he doesn't need it for performance IF the pipes are short enough.. if he's pushing it to the rear axle, those pulses get lazy and become denser as they cool.. and create an obstacle the next pulse has to push through.. effectively creating backpressure..

a cat gets really hot, which heats the cooling pulse back up to near what it was when it came out of the head.. that heat creates an area of low pressure and effectively becomes a vacuum that draws the pulse of exhaust to it.. but he's running without a cat, and therefor losses that.. which means, he needs all the help he can get to clear the slowing pulses out of there.. and x or h pipe do just that.. they tug on exhaust pulses while the cylinder is pushing- which means the pulses aren't relying solely on being pushed out- they are being pulled too- and hopefully move fast enough to not cool to the point the pulse behind them has to push them..

cats promote scavenging almost to the the degree they cancel out the obstacle they also create- and because they get so hot.. An X, Y or H use the brief moments nothing is pushing through one bank by relying on the other bank to maintain the momentum of flow.. flow is good..

if he's running all the way to the **** of the truck, it's my point he needs a commonality to get that done efficiently.. that's all I'm saying by interjecting he NEEDS an x or h..

 

I'd be running two hi flow cats