First off, you dont have that much stuff done to your car either. I had full exhaust on mine too and dynod 207/274. Youre not that much farther ahead than i was. Figure 215-220 max. At 3400 pounds i think it would take one hell of a stick jockey to get a 13.8 out of it. I dont know for sure, but i know those civics can get really light. Wouldnt surprise me if your third gear synchro is going out and you had a smaller powre to weight ratio.
Secondly, i think being faster than the next guy is one of many wrong reasons to own ANY car, fox included. You say you called him out. Was he talking smack, or were you? If he was talking smack, i probably wouldnt have raced him in the first place. And im definitely not one to start something. Regardless, i think you should buck up and take it like a man. So he beat you. BFD...If thats enough to make you want to sell your 5.0 then please, do so. There are many of us out there who would love to have a car like yours.