so i want to hollow out my cat and then reweld it back in but i hear that a smog tech can hear whether or not it has been hollowed out or not. is this true? thankyou

 

I personally would prefer keeping the stock cat intact and getting a delete pipe. The cats are expensive to replace if you need to put on a working cat back on. For 125 bucks you can get delete pipe or 500 for a stock cat from the "stealer".

And its very easy tell by the smell of the exhaust if the cat and egr is working properly.

That just my 2 cents

 

If you get the full front pipe, it will take about an hour to put it in the first time. Or you can buy a couple of the V-band clamps and have them welded onto the exhaust pipe, the cat, and the delete pipe. When you need to have it smogged, undo the 2 clamps, and install the cat. Total time that would be about 15 mins (including getting the tools out).

 

X2