I doubt one from an 01 would fit as it was a different body style, and cold air intakes go outside the engine bay and thus have to be the correct design for the frame and body. I dont actually know who makes one for the 03 but just check the typical companies or wait and I'm sure someone here will help you out with a specific company.

 

Yes, an intake for an 01 RS will work for an 03 RS. Whitelegacy doesnt know what he is talking about (no offense), unless of course you are talking about an 03 WRX, in that case they are very different...

 

i saw someone with an Injen Intake for their 03 rs
i was tailing him on 280 for like....6 miles and i saw his license cover with the Injen Logo

im sorta tempted to get an injen intake but i dunno how much it will cost or if it will have any increase for my 03 rs

 

280 is about right for the cost actually... Somewhere around there. I say get a Cobb intake instead, a little less expensive, but you are looking at ~5-10hp gains via either one.

 

Go with the Cobb CAI, I have it on my '00 Legacy and it made a pretty noticeable gain + sounds cooler than ever.

 

http://cobbtuning.com/impreza/