You have to remember that Chris Shenefield has about 10 years of autocross experience under his belt. And that Si he had definitely wasn't a daily driver. I drove his car at a local event and it was a street legal go-kart. My first time out in the car I tied his fastest run. My 2nd run I was .2 seconds faster, and my 3rd run I had a passenger in the car and got the same time as my 2nd run.
I ended up with a 30.1. In my car (2000 Honda Civic Si) with 8 runs I got a 30.5'ish. Weight had a big factor in his car, but another thing was power delivery.
I think you might do well locally with a DX, but the extra HPs and torque will help alot.
With my car if I was able to shave another 100-200lbs I would be on par with Chris' car. But he sold his 1989 Civic Si fully equipped for $5000. I wish I had the money :0
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