[saintz]

If you already have deleted the secondary cats, I would leave the primaries and do short tube headers. You could do short tubes now (bolt on) and then down the road replace your primaries with high flow cats when they start to go bad. And yes, you'll get a CEL when you remove the primaries, regardless of whether you have secondaries or not. The sensor is located between the primaries and secondaries, so it only checks if the primaries are working or not. Typically, the difference between a single cat (especially high flow) and no cat at all is only a few HP, i.e. not enough that you can notice or measure. Having the primaries in place isn't going to hurt you.