[mjorgensen]

The condition you are describing is "soley" caused by the high flow cats and not the Corsa exhaust. We have sold arguably more Corsa exhaust over the years than anyone and have tested back to back. There is a silght movement upwards of the power band as there is with any header/exhaust upgrade worth doing but the lack of low end torque is more often caused by the cats. I have since stopped removing perfectly good cats for the 3-4 hp improvement on "top" for the improved torque and reliability the stock cats and 02 placement give you. But this is just my 2 cents ;-)