URD equal length headers for Canada

Thinking of installing these URD equal length headers as soon as I pass my next Air Care in Sept as this is the last year they will be doing air care testing in British Columbia. I have a few questions which some of you more experienced engine modifiers may be able to help me with.

1) How much of a power and MPG gain can I expect from these long tubes approximately?
2) Since they will be eliminating the catalytic converter build onto the stock exhaust manifold I'm wondering how much louder the exhaust will be if I maintain the stock resonator and muffler?
3) Are there any other parts I need to buy to make this work after taking off my stock exhaust manifold (i.e. the wire that attaches to the old exhaust header, or something to prevent the engine light from coming on.

Thanks for any tips you can share as I am new to this forum.

 

1- Probably 20-25 HP between 3500-3750 rpm. About the MPG gain, forget about it. Somes here will not be ok with that one, but more pwer = more fuel.
2- Which resonator you're talking about? What you will have is the second bank of catalytic converter and the muffler. The exhaust will be a bit louder over 3500 rpm, mostly at WOT.
3- On URD site, the O2 plug and play simulators and 2 gaskets between the headers and Y-pipe.

 

How did it go? How much did you end up spending on them?