The civic Si doesn't make much power until you get in the upper rev range so he's driving it pretty much appropriate for the way the power band is designed in the honda.
be prepared to pay list or very close to list on a ms3...plus you'll take a bath on a trade...heck i just bought my ms3 2 weeks ago and put only 300 miles on it so far...if i were to trade it in right now i'd probably lose 2k probably more...and my car is flawless...
try to be happy with the Si...it's a nice car...it's the cheapest way to go (keeping it).
Sorry, I've never driven the Si before, but I didn't realize you'd have to always hit the peak powerband just to move the car or pass someone. I've driven an Integra for 3+ years and rarely had to punch it into high RPM.
Anyways, I understand the OP's situation. I want to trade up to a MS3 only after a year of owning my regular Mazda3. I know I"m going to get bent over but I'm going to see what I can get for my car first... (see my accident thread... so I'm actually going to get bent over twice.) I'm back and forth as to whether to just drive my car and mod that one or really go for a MS3.