A stock 99-2001 Si (SiR here in Canada) puts down 131-135whp usually. A good friend of mine has one and we screw around sometimes (with one of the 2 cars on my sig). The DX being 100% stock loses by quite a bit, I'd guess it to be exactly 1 second slower than whatever he is running now, so maybe 15.7 to 16.7 (his car was reverted to stock but only has a body kit on it), against my probe it would be a waste of gas, but when the Si had intake, header, exhaust, FMU, fuel pump and JRSC supercharger @ 11lbs boost (different pulley), he was about even with me on the highway. At 13psi he was a little quicker (but that came at a cost of having to run strictly 94octane + octane booster.

Si's tend to run between 15.1-15.9 depending on driver skill mostly and also elevation (in certain areas, getting consistent high 15's isn't easy even with a good driver)