Which high flow cat is right for me?

I have the 2.5" Magnaflow catback system on my 1997 3.8 and i am about to buy either a carsound or catco high flow cat. what is the right part for me...size, etc.?? also if i already have an 02 sensor after my cat on the S-Pipe will i get an SES light??

Ide stick with a magnaflow, just to keep it all matched.. Get a 2.5" cat.. You dont want any bigger.. Magnaflow make an obd2 friendly cat converter so it should work well with your o2 sensor.. I believe its the 43000 series? im not sure.. check out a magnaflow website, or
www.car-sound.com