This modification is about as simple and easy as they come -- just open up your 03-05 SRT-4 factory air box and replace your flimsy factory paper filter with a high-flowing K&N air filter. This will allow your SRT-4 breathe easier without extensive modification to your factory intake system. Backed by K&N's famous million mile warranty, the K&N replacement air filter is virtually the last filter you will ever need to buy for your SRT-4.