Let me start by saying I have seen several posts on this forum and on the RSX forum debating the performance between these two cars. I love both of these cars and if the RSX had come out a little sooner it would have been a seriously difficult decision between the two of them. I typically do not post on forums, just browse for useful information but I have finally decided to share an experience of mine. Hopefully you will find this helpful.
My good friend purchased an RSX-S a couple of months ago and ever since he bought it we both wanted a chance to see how the cars compared. We finally had a chance a little while ago to really compare the ability of these two cars under several different driving conditions. Let me get out of the way that his car has roughly 7,000 miles and an injen intake. My car has roughly 17,000 miles and a MBC set to 15 along with several stereo upgrades.
We met up on a dry sunny day with the temp around 70. We drove off to our favorite deserted stretch of road in the back of an industrial complex that is completely empty on the weekend. There is a great stretch of road that I can get up to about 105 mph on before slowing down, so I figure it's at least a 1/4 mile long.
So here are some of the results. First we started off with a simple 0 - 100 or so run. After several attempts I would typically have 2-3 cars off the launch and pull to about 5 - 7 by the time I hit 100. Hard to say exactly, but there was a good bit of ground between him and me in my rear view mirror. Next I would allow him to gain traction and actually move about a car length ahead before I would launch this race was closer. After launch I would be about even with him by the 1-2 shift and by 100 he would be roughly 3-5 lengths back depending on how we launched. In order to confirm these results we each switched cars for a dozen tries and aside from him bogging several times, once he figured things out the results were exactly the same. Basically the RSX didn’t have much of a chance if I launched from a stop.
We next moved on to a couple of longer open 4 lane country roads where we were able to give the rolling start races a go. Neither my friend or myself race above 80 on these public streets even though no one was around. I don't care what the results above 80 are because you will not find either of us racing above those speeds. Anyway, we first started with 15 - 80 runs and the result was typically me pulling about 2 - 3 cars by the time we had to shut down. We next moved up to a 30 - 80 run and the results were a little closer but I was always around 2 cars lengths ahead. The 50 - 80 results were even closer, depending on who stepped down on the gas first but it appeared I would always nose ahead until he was at around the rear passenger doors. We again switched and allowed the other a try to make sure it was not driver error, very similar results. I will say it appeared the RSX was at least hanging even if not gaining a little right around where we began to slow down. I don't now what would happen above 80. But I would guess unless the WRX really crapped out the RSX would probably pull even a little over 100.
We both agreed with the cars in their current mods there was really no way the RSX was faster. The RSX certainly performed very well and somewhat better than I expected. I would imagine if we were both stock it would be a fairly even race from a roll at the speeds we tested. Please keep in mind I consider myself a fairly good driver, but I have never taken my car to the track to confirm this.
I have attempted to be as impartial and objective as possible. I hope this was somewhat helpful. Sorry about the length of the post!