That really depends on how much money you want to spend. Mine also died not too long ago and I just replaced it with the oem one from cummins. I don't know how much power you have, but if you're planning lots of upgrades and such choose a FASS or RASP. The rasp would be my choice if I had big bucks, but I'm planning on running the FASS. You can get the fass without the filters for pretty reasonable and run it in tandem with your factory one. That's why i chose to simply r/r the factory one and than put the fass system on when I get the money. It's a pretty good unit from what I hear and I'm sure others will let you know what they think.