You need to drive the MR2. It’s really just a matter of getting over “3rd gear-itis”. As long as the car is good on torque, it pulls well in 3rd, and if it doesn’t have good torque (like a Type R so I’m told), it doesn’t pull well in 3rd. Most people are just afraid of loosing time in the downshift back to second, because it’s easy to screw up. I don’t know, I don’t really have any data to back any of this up though, it’s really just a “butt dyno” type thing.
But to not go too far off topic, if the Si is like the Type R, you better get working on you 2nd to 1st shifting 
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