[DRASTiK]

Well I probably can't answer everything, but I'll do what I can.

Your heat problem could be a bad water pump, or a blockage somewhere. It's also possible that moving up to a 180 thermostat will actually keep it cooler because a 160 basically stays open all the time, and therefore doesn't give the water enough time to cool in the radiator. A flex fan would cool it a little better, but it is much more dangerous than a clutch fan and it will rob you of a few more horsepower than a clutch setup.

If you lose the cats, you don't need a chip. Whoever told you that was just plain wrong. I have an off road H-pipe and no cats, just like many members here and we don't need chips.

The K&N issue can go either way. If you're still using the factory air box, then they sell a K&N filter that fits right into it. If you're using a fenderwell induction, then you could still just buy a cone filter.

Cheap performance mods, are a fenderwell air induction system, bumping the timing up to around 14, but make sure there's no detonation. If the air silencer is still in your factory airbox, then remove it for a couple of horses.

There are many different things beyond that which you can do, but we need you to tell us what kind of performance you're shooting for and we can guide you onto the right track from there.