Thinking of installing Screamin eagle stage 1 air filter on my 03 ultra with stock exhaust. Parts guy at Harley say I can get by with no stage 1 download.
Any input??

 

Since you don't have O2 sensors you are probably OK. Why are you changing the air cleaner? If you are changing it for performance gains don't expect any without also changing the mufflers. Maybe 1 or 2 hp above 4000 rpms.

 

The air flow rate will be based on your most restrictive part. Think of blowing up a balloon with your mouth vs. blowing it up through a straw. In your case the exhaust is the most restrictive part. The reason for the stage 1 download is because a increased airflow will cause the engine to run too lean. The stage 1 download compensates for that. If you don't upgrade your exhaust the stage 1 download will make the bike run too rich. Hold off on the Stage 1 download and/or tuners until both your air cleaner and exhaust are high flow.