About to buy either a 2010 6.4 or a 2012 6.7 from what I have seen the 6.4 tuned is stupid fast compared to the 6.7 tuned I thought with all the hype of the new motor it would perform way better. Also I'd like to know how the spartan compares to h&s on the 6.7. And how's the reliability of both trucks.

 

What do you want to do with them? Tow,DD,go fast, all the above?
If you are going do intake,exhaust,tuner I would go for a low mileage 6.4 because they respond to performance mods better than the 6.7 right now. However 6.7s have nicer interior new trans, more creature comforts, get good mileage stock unlike the 6.4. Both are very technical motors but there are really not a lot of problems with the 6.4s right now other than the earlier radiator problems on the 08s but if you are going to do an EGR delete and DPF/DOC delete I think you would be in good shape. As for H&S and Spartan, I would go with H&S for both motors. This is because I would get KEM tunes on my minimax or blackmax if I went that route for the 6.4 but its more or less preference other than that. As for the 6.7 there have been some problems with the dashdaq not reading all the parameters on the new trucks, dont know if thats been fixed yet or not.

 

The 6.4 can be done up a lot more but they have more issues. The 6.7 is stock 410hp and a tougher trAnsmission. Spartan is the best to get