plugged cats and increase in hp?

[varanus]

Hi all. I'll soon be putting on a 3 inch corsa with Random tech cats on my 97 gts with 28,000 miles. QA couple of questions-
1. I have seen posts about stock cats plugging up over time and robbing hp. Does anyone know how long it takes for them to plug up?
2. I also saw posts where some people installed cat back exhaust with either little gain or even a loss in power. Something about mismatching sizes of tubes where exhaust pulses are slowed down because of this. Any feedback?
3. Finally, I am considering headers. How much power is gained with my new exhaust system and then adding headers. Is it worth the $$ vs hp gain as headers aren't cheap?
Thanks

 

[SapphireGTS]

Check your email.

Headers are $$$$. Do the cats and corsa. I think you will be so happy with the sound that you wont care about gaining all that extra HP

Any cats can clog but I have not heard of this more so on vipers

Good luck