I just recently put straight pipes on my Chevy cut the muffler out and bigger pipe as well professionally
Was wondering if I remove my cats completely would I lose back pressure or power or etc?
Just curious before I decide to put high flow cats seeing what would be better?

 

it is illegal to have no catalyc converter. you could be hit with a big fine.
Power gains would be minimal at most, in some cases the backflow slightly reduces power

 

Dependin on where you live you can get away with it. I don't run cats on either of my trucks but my county doesn't do emissions. You'll need a tune or Somethin to trick the rear O2 sensors to make it think the cats are there so it doesn't throw a light.

Also back pressure isn't what you should be concerned about. You want that gases to flow freely and get out quickly as possible. Yes you want some(minimal) back flow but it's not as big as its made out to be.