cats & o2 sims

Anyone know of some low profile cats? or some good o2 sims?

thanks

O2 sims are a waste of money. Cheaper to find someone to turn off the codes. That is all the sims do basicly.
Magnaflow has decently small hi-flow cats.

Thats the hard part is finding someone that can turn it off here. That is why I was wondering about programmers that I can do it myself and get some more hp out of the motor by changing parameters...

The ones that allow you to turn them off are pricey.