Four stroke engines dont need back pressure in the exhaust, they actually need low pressure in the exhaust behind the exhaust pressure pulse to fully draw the exhaust out and help pull the intake into the cylinders. If you have a high pressure in the exhaust you are hindering scavanging for the next power cycle. When a cylinder fires it causes a high pressure wave from the combustion, as it leaves the head and travels through the exhaust it creates a low pressure behind it as it travels. The whole down fall to the drag pipes is there is no scavenging effect from the other firing cylinders and often times the drag pipes are to short to create enough of a low pressure area behind the closed exhaust valve. A long drag pipe would work better then the short common aftermarket drag pipes. Thats why 4 into 1 and 4 into 2 exhaust work best on the 750 as the exhaust flow from the previous fired cylinder creates a low pressure area behind the pressure wave which draws the next firing cylinders exhaust charge out. I do agree that drag pipes cut power on the 750, the only reason to do it is for looks and for sound. If you are looking for all out performance 4 into 1 or even a 4 into 2 is far better then drag pipes. The stock honda 4 pipes work so well because of there length and in the HM300 pipes they work better because of the straight through low restriction muffler area.