There is so much in terms of variables that even if you feel like you are matching what you can, it can still have an effect on your overall run. I wouldn't be going as far as to saying your exhaust could be the reason behind such a difference yet. After all, the difference you are dealing with here is only 200 milliseconds. It's not unrealistic to consider just your normal atmospheric or driving variables to be causing this difference. Two things however: 1) Reaction time does not have any effect on your 1/4 mile time. Take advantage of that and use an extra second or two to put more focus into your launch. It can make a difference. 2) I would not be expecting a 0.7 second improvement from just an exhaust and intake alone unless your stock ones had some serious issues. To give you an example, from my experience, the fastest time on my TRD Aurion was only 0.76 seconds quicker than that of my Aurion Sportivo. These two cars had a measured power difference of 40kW at the wheels. That's not to say one or the other could have performed better, but when you are dealing with things like this, there is a fair amount of variable.