Well, my friend and I were driving home from a club this weekend and we decided to have a little fun on the wide open highway. He had one extra passenger than I did and we did two runs.
First run, no honks we just lined up at 60mph and he got the jump. He jumped out to a quick one car lead and we stayed like that with him slightly gaining and then I shut down at about 90mph because I saw a car merging up ahead. He had about 1 1/2 car lengths between us.
Second race we lined up again at 60mph and this time I started the 3 honks. He had a delayed reaction so I jumped out in front first. Couldn't really see him so I know he was probably right in my blind spot. I wind out all of third gear and I still can't see him. I know he's gonna be coming up any second now... I shift to fourth and I see him in the corner of my eye and wow that m3 motor sounds awesome. Fourth gear is a dead gear for the WRX as we all know so he pretty much shoots by me and gains a car length in no time. I shut down after that because 1) we're going plenty fast already, about a 100mph and 2) I know it would have just gotten really ugly with the M3 topend.
Overall, I was very impressed with the results because I'm giving up 50hp or so to the crank 280hp vs 333hp, so I'm sure whp is even more of a difference. I've raced this friend before on the streets but he made excuses and didn't want to run from a stop so we did 15mph roll-ons. Pretty much same result but he would always jump to a quick lead and slowly pull to about 80mph where we would shut down with him starting to really pull. I would really love to take him from a stop. I bet I could probably hold him to about 70-80mph before he passed me.