According to their dyno, it seems that all are gains. This of course is with a reflash, without one you may get half or a bit less than the advertised whp. The test pipes require a cut after the original cats, and then using the supplied clamps you bolt the front to the headers and clamp the rear part of the tp to the oem xpipe. To return to stock cats, you do the same, bolt front and clamp rear. What i don't really understand is how these could make a whopping 40whp when full exhausts without primary and secondary cats only see about 28whp. The only explanation i could think of is all the exhausts advertise gained whp without a tune. I would definitely get these, i had ordered them but weren't in stock. The only drawback is that if you're leasing your car, you these tp's required cutting the stock exhaust and they might give you trouble when returning the lease if they happen to look under the car.
