Yup. I grimaced with each purchase. But guys and gals, the best price for OEM cats were $559.00 each. I bought them off of a Infiniti dealer on Ebay. Ebay store (pepeinfiniti). My front pipe heat shields were shot also. The mid pipe with the resonator was bad also. I have a Walker muffler on the rear.
So installing it yourself. Cost of both OEM cats is $1118.00. You should change all your 02 sensors. That is going to run $300.00. So the cheapest you can do it installing yourself is $1418.00. You could pay someone to install them for $300.00 if you look hard enough.
The second best price you can get on OEM parts is a Infiniti Online parts Dealer website. But beware. Not all dealers charge the same price. If you look up the price of catalytic convertor on the infiniti edison (Ray Catena), the price is about $1400.00 with core price. I stopped by Ray Catena Infiniti dealer parts counter a couple of weeks back and the over the counter price was $862.00 + $140 core for a total of $1000.00.
However I did find a Ramsey Infiniti dealer that was selling parts online also and price was close to the ebay price. The only issue there was taxes and shipping. I had planned to pick my part up but in the end I decided to get 2nd cat, front and rear pipe from PepiInfiniti. I received and bought one cat from pepi already. It came next day from NY, which was about a 1.5 hour driving distance to my house.
http://infinitiofedisonparts.com/infinitiparts
http://ramseyinfinitiparts.com
INFINITI 208B2CG725 GENUINE OEM FACTORY ORIGINAL CATALYTIC CONVERTER $699.20 (includes $140.00 Core price)
INFINITI 208B3CG725 GENUINE OEM FACTORY ORIGINAL CATALYTIC CONVERTER $699.20 (includes $140.00 Core price)
INFINITI 20300CG000 GENUINE OEM FACTORY ORIGINAL RESONATOR & PIPE $329.92
INFINITI 20020CG000 GENUINE OEM FACTORY ORIGINAL FRONT PIPE $393.02
Bought front and rear 02 sensors from NGK. Rear part# 24408 and 24404. Front both sides are part 24320. Found the best price on the 02 servers between Amazon, ebay and rockauto. Averaged about $68 each. I believe NGK is the OEM manufacturer for NISSAN.
http://www.ngksparkplugs.com/part_finder/car_truck_suv/results.asp?engineid=27528
I wouldn't risk putting HFC's on my wife car. Mainly due to the possible noise factor. I have a Borla cat back exhaust on my Corvette and that's a little noisy for her. If I was building a high performance FX35/G35 and wanted high flow cats, for myself I might purchase them. The only other issue I see there is no heat shield on the cats (which made me look at my Corvette original exhaust pipe and there is a heat shield on one side of the front Y pipe and the Borla doesn't have it of course).
Bosal makes a front Y pipe and resonator pipe. However there is no heat shielding on the front y pipe.
One of my coworkers put after market cats on his 2002 Maxima. He said he was sorry he did it because it made it sound like a sports car. He mentioned he should have spent the extra money and gone OEM not to deal with the noise.
However, he's as much a car guy as my wife. BTW, he recently bought a Infiniti G35 Sedan.