Planning ahead right now...truck is all stock,  maybe later add little power (not much) ...right now exhaust is 3 inch.  What benefits would 4 inch do from exhaust brake to exhaust tip?  Lower egt some?  Do I have to modify anything?

Thanks

I went to a 4 inch MBRP exhaust I am completely stock as well. No modifications needed. Lowered my EGTs slightly but nothing to write home about. Sounds better is all real benefit I got. Stock exhaust was rusted out.

Went from 3" to 4" and ZERO change in EGT's. Tunning on the Quadzilla does more to change EGT's than exhaust does. 

 

Drone is louder. The exhaust brake is louder. 

 

I did a 4" Diamond Eye Aluminized exhaust system with muffler. Cruising is quiet. Power band pulling up grades there is a spot where drone gets loud in the cab. Then every time I break over the top of Midvale grade and start hitting the exhaust brake coming down the back side its rather on the loud side. 

What about towing? Think it would help egt's any if you were towing a heavier load?  (Sounds crazy to me on the surface but towing 8 or 9 k trailer, the exhaust would have less resistance exiting) 

3" isn't a restriction on a stockish truck.  

Like this time around I looked at your signature... 2001 Cummins will have the HY35 turbo...

 

2 hours ago, 015point9 said:

(Sounds crazy to me on the surface but towing 8 or 9 k trailer, the exhaust would have less resistance exiting) 

 

The biggest choke point is your HY35 turbo with a 9cm² housing compared to HX35 with a 12cm² housing. This would reduce EGT's more than 4" exhaust. 

 

 

Mine is 5" not sure of brand po put it on, I don't have any real complaints about it. To each their own I guess.

The only real benefit on a stock-ish truck would be that lovely Cummins sound.