33 66 mixes rupturing pipes too often?

[Amuys]

I remember that I used to be able to have a single plasma tank in cold and hot loop, and a 33plasma 66O2 tank in combustion with vents open and that used to be able to power both loops up extremely fast. The pumps are set all to 5 save the combustion which is set to 1. This does not work as efficiently anymore as cold loop takes much longer to start up (about 15 minutes) and by then, several of the hot and combustion pipes would be ruptured. My old setup used to be able to get into the hundreds of gigawatts while the current one only lets me get into about 50 megawatts at most.