Not really. The 05s have a rev up motor, the lower plenum was addressed, but you just cant use the spacer to gain the most power. You have to buy the M REV kit. THe HP #'s are more of a marketing scheme more than anything. They say the 03/04 sedan is only making 260bhp, thats been proven time and time again with dynos that they are actually making at least 280bhp. Most are dynoing 225-230whp, given a 17-18% drive train loss for the 6 MT, that is more than 260bhp. I just dynoed 3 weeks ago with only a pop charger and z tube, 233whp. You look at all the tests from each year, do any of them look faster than the other, NO. The REV UP motor makes more power up top, allows for 7100 rpms, but makes less torque down low than the non rev up motor. So basically making more power up top is cancelled out by making less torque. Plus you have to take in account that the 03/04 sedans are lighter than the 03/04 coupes and 05/06 sedans and coupes. So, they add a few more ponies and slap some more weight on as well, pointless, since we know horsepower/weight is the key.