1) Add high flow intake pipe from turbo to factory air box
2) Use high flow K&N air filter
3) Add DPF to tail 5" exhaust
4) 6.7 Smarty

I have 39k on my 07.5 and get 18 on highway

That is not bad fir 9500# dually with 4.10s & 19.5s

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CUMMINZ NC
2007.5 CTD, QC-DRW 3500 BFT Laramie, Smarty S-67, AMSOil Dual-Gard Bypass, Custom Line-X 4x4, 4.10LS, 988s, 68rfe, MBRP 5", Mobil Delvac. Yukon free spin, 19.5x245 G647 Goodyear's - 2006 - 37RLTSD Cedar Creek-Day Dreamer
My 2007.5 DRW Truck at www.CumminZ.com