Which is better for an impreza RS, cai or sri?

I have an '05 RS. want to do simple mods to it, any suggestions?

Depends on if you want to have more to lose a little torque and get some hp, or get some torque and lose a little hp.

CAI will give you a bit more hp throughout your power band, while sacraficing a little low end torque. Also like mentioned, there's a risk of sucking up some water, but a water sock comes with the K&N Typhoon system.

SRI will give you a bit more torque at the bottom, but will not perform like a CAI at the top. attempt and find one with a heat shield, temperatures under the hood can get pretty hot, and sucking in hot air is inefficient.

As for other simple mods. You may want to look into a good pair of spark plug wires, 9mm, and a nice set of plugs, NGK or Denso Iridiums. Accesory pulleys and an underdrive pulley will give you a slight power get. Then you could go a bit more and do exhaust and header, but if you get a header do not get equal length and ruin the great boxer engine sound.

1991 Subaru Legacy owner one year
2000 Subaru Impreza 2.5 RS owner two years
2002 Subaru Impreza WRX owner one year, 375hp
2007 Hyundai Tiburon SE owner two months

if you do not live in a flooded area. then I propose to get a CAI. AEM, K&N, Injen are good brands out there. before doing that, I also propose to get an AEM bypass valve. In that way if you go to a flooded area, it will not suck up water from the bottom. CAI is better. Cooler air gives you abit more hp than the SRI.

From what I have seen, CAI for NA and SRI for Forced Induction. The NA will gain from the cold air, where the turbo heats up the air enough anyway to partially negate the difference.

neither. take the silencer off of your stock air box and get a K&N flat filter for it. it's generally short ram then. plus its free, and easy, and you do not have to worry about screwing around with sensors. and exhaust won't help. it is an N/A.