Interesting exhaust info.

Years ago a friend and I each owned 1969 Triumph Daytona 500 motorcycles. They were the scourge of Riverside and E st. San Berdo. If my friend and I were not blowing the doors off some one's ride we were racing each other. These bikes were identical to the point we shifted at the same times but my friends bike would consistently pull by half a length every time. One time we were heading up to Big Bear with our wives and I was a bit ahead of my buddy and his wife. It had rained and a car had hit a rock and broke it's oil pan letting the slippery stuff run across the wet road at a curve. Luckily I wasn't going very fast but when I hit the oil slick in the turn my bike went down dumping my wife's and my butts on the road. My wife banged her knee and couldn't sit on the bike so we stayed in a motel that night and next day left the wives in the room and rode back to Riverside to get a car. On the way back we raced each other and my bike would win by a full bike length. As far as we could figure the left exhaust pipe got a ding in it and the back pressure somehow changed enough to give me the edge. Then there was my 128 with a 79 strada 1500. It was balanced had a rally cam and some other mods and did pretty good for a Fiat. I made a 4 into 1 header with 1 1/4 tubing into the stock exhaust pipe and by the seat of the pants dyno felt a little peppier. There is a two mile clime that I use as a testing area and the car felt like it pulled that grade a little better with the header so I figured bigger pipes might do even better so I built another header with 1 1/2 tubing and did the rest of the exhaust in 2 1/4 inch pipe. The car was a dog pulling the hill so I went back to the smaller pipe. Now I am a certified shade tree mechanic so I go by what I here and some experimenting so I have heard and experienced to some degree that smaller pipes can give better low end in some cases.
 
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