WGibbs,
Any kind of filter helps, but the stock replacements are mostly a money savings as you can re use them. We have a special clearance sale on the 2003/04 only Stage I AFE Pro Guard 7 systems on our site while supplies last anyway. It's a way for you to get a deal and still get a PG7 Stage I over a stock drop in etc. Call us if you have any questions etc.
Mark @ DPPI