The 04 has a different fuel map, and most of the performance parts for the 05 have different part numbers than the 04 or 03.

 

the only performance parts that are different for the 05 are the stage ecu's, and that's due to the programing because of the lack of a battery temp sensor.

 

Did they make an ACR version of the 04's?

 

nope

 

Well there's your difference for 05. Optional ACR package which gives you the 16x7 BBS Aluminium Rims. Tokico shocks and the Viper seats set up to take a 5 point harness. (though I opted out of the viper seats).

There is also a Special Edition released in 05 (not sure if they released this one in 03 or 04) but your get a special edtion package that give a serial number on a certificate and also embroidered into the dash. Unsure if you get any actual perfomance upgrades to the car.

 

I have the 05/ It is a little stiff sometimes to go into 3rd ( when cold) As far as the 04 being faster, I have raced 2- 04's ( 1 with a stage 1, my brothers) Neither one beat me. We swapped cars and raced, it was side by side. Mine runs very strong. All I have in mine is $20 occ/ Denso iridiums/ 9mm wires/ K+n drop in filter.

 

Everyone expects their car to perfrom exactly like, or even better, than the one they read about in the car mags. It ain't gonna happen. Factory tolerances vary slightly from day to day and assembly line workers are human, it's a well known fact that cars built on a Monday, for example, are generally further "out of spec" than cars built during the rest of the work week. Add in differences in gasoline quality, outside air temp, how much junk you're hauling around in your trunk, the driver's skill level, tire pressure, engine break in procedures, and about a dozen other variables, and you can start to see why two of the "same cars" will not have identical performance.........

Dusty

 

Very true. With a little research and TLC you can overcome alot of the problems or issues that may affect the performance of the car. As for the tooling being long in tooth...doesn't really sound realistic. Yeah this is the end run for the neon with the 2.4L, but not for that motor. It all comes down what dusty said...performance varies throughout the years, statistically I think it's been found all 3 years have averaged out.