[RICK LAKE]

Dangerous Doug The problem with side pipes is not enough mixer from all the cylinders in 1 spot because how short the area is after the collector. Having a side pipe with small muffler inlets and outlets helps get more back pressure and a better reading of the A/F ratio. They have a clip on kit for just checking the A/F with the car running. Not sure if they stay in place on a road test with out screwing them(clip) into the outlets of the side pipe.
Mine are as far back as I could get and still be in the header pipe. The other thing is using an infared gun for exhaust temps on the pipes. Want the temp to be about 100F or less for a well running motor. Around 1,150F to 1,250F is a good number. Any higher and you may be running lean or too much timing. Going to a chassic dyno and spending $500.00 is worth it to get the best all around performance out of the motor in all conditions of weather. Rick L. Ps wide ratio O2 sensors are better than narrow ones. Want to see how rich the motor goes on accell. The old numbers where about 12.5-13.2 A/F for most motors. Last couple of years they have gone up to 13.5-13.7. I stay soft and a little rich. Spark plugs are cheap to replace or clean against melt down in the holes.