justen - thats exactly what i was going to say - for a few HP - do you want to have the risk of an unroadworthy , and therefore illegal streetcar ?
If your concerned about power - just get a proper 3 dump pipe + performance exhaust made up - with a high flow cat moved back further than where the stock one is ..
youd still get a few more neddys from having none - but at least it would be legal .