The last few times the 456 got out, the tachometer is not working and the throttle response is very sluggish. Almost like a limp mode. No lights are present on the dash. After 4-5 miles, all of a sudden the tach springs into action and the car builds revs as normal. Recent modifications include - Quicksilver cat bypass pipes, Braden center resonator bypass, BMC air filters. Not sure what the issue is, but guessing it is something related to the recent changes. Any insights would be great!