Hey Guys,
To give you all some background on my car.....
1997 Honda Civic EX Coupe
- 2000 Civic EX D16y8 SOHC Vtec Motor (swapped with 40k miles)
- Cold-Air Intake
- 4-2-1 Headers
- Cat-Back Exhaust System
- MSD Super Conductor Wires

Recently, i had to drive back up to my school in Detroit, Michigan all the way from MIAMI, FLORIDA. While I was driving up I had my Exhaust Silencer on. About 400 miles into the trip, my CHECK ENGINE light comes on. So when i get to Atlanta, Georgia i take my car into the local Honda Dealership. They said it was probably one of the O2 Valve sensors or something like that. But when they were in there, they also found other problems, like a mis-fire in my 4th cylinder. So they put in a new updated ECU which was all covered by warranty.
However, when i got the car back, I noticed a SIGNIFICANT POWER LOSS. Mostly in the low RPMs. Its not like my Civic had alot of low-end power to begin with, but it feels like it has even less now. I'll floor it at a stoplight, and there is nothing. Before it used to take about a second and then a little kick would come. But now, there's just nothing there until the VTEC kicks in.

Anybody know what this could be? ? ? I would think if i had a mis-fire in my 4th cylinder, and now i dont....i would think my car would perform BETTER. Any ideas ????