I purchased my first diesel in June 2011,Dodge Ram 2500 Mega Cab Laramie. I'm looking into getting an exhaust for the truck. It comes stock with 4" tubes. Whats a good exhaust system? I'm aware that there are DPF deletes.There are turbo back, cat back systems. Whats the advantage to 5" tubes over 4" and what would you vet diesel owners recommend to get? I saw a Magnaflow Black Series that looked interesting. Also whats one of the better programmers? I don't want the programmer for speed ,towing. I want better fuel milage and reliability,don't want to be servicing my tranny anytime soon!I have a 70 Buick GS for burning down the track. I don't want a screaming banshee sounding diesel either but a healthy sounding one. Muffler? No Muffler? I'd appreciate any insight into diesel exhaust and programmers.