I have come across 4 injectors still on the rails and don't know the size.How can I tell,they are orange if that matters.

 

What size injectors does my RX-7 use? What colour are they?
Year Engine Plug Size Colour Part #
84-85 13B NA, low square center, 680cc, orange, 195500-0900
86-87 13B NA, low square center, 460cc, red, 195500-1350
86-87 13B Turbo, low square center, 550cc, tan, 195500-1370
88 13B NA, high square offset, 460cc, purple, 195500-1350
88 13B Turbo, high square offset, 550cc, purple, 195500-1370
89-91 13B NA, high oval center, 460cc, red, 195500-2010
89-91 13B Turbo, high oval center, 550cc, purple, 195500-2020

From the FAQS post above. Just try to match up the numbers/color and plug style

 

I did a cat delete,cat back and now I'm hitting fuel cut.Will they be good for my 87 TII and will I need some kind of fuel management system.

 

fuel cut isn't being caused by your stock injectors, assuming everything is stock. It's your ecu that cuts fuel because you are now boosting higher with the reduced backpressure. all you need is a fuel cut defender, you can search for more information on it, and can find them from racing beat, hks, mazdatrix, etc.

 

Or you can find one on the classified section and find one for like 20 bucks.

 

for reference,if you use bigger injectors like for example from a GSL-SE, or any aftermarket ones,you'll need a fuel controller to be able to run the car w/ the new injectors.