Cooler EGTs, better mpgs, and a little better spool-up are just a few benefits from both 4 & 5 inch systems, better than stock for sure. 4 inch is plenty big unless youre going for serious ponies upwards of 500. You can change the sound with different mufflers, or straight pipe it altogether 5 inch would be a PITA IMO.

 

I didn't notice any difference in EGT's when I pulled off the stock garbage and put on the 4" straight pipe, and my mpg actually went down. I think it made in infinitesimal difference towing, but not enough to justify it. On a stock truck, it's just more noise.

 

Is this a "new to you" truck? Any mods or goodies to put into your signature?