Fitting a Scorpion exhaust

Just got a good deal on a resonated scorpion catback. I'd like to install it myself, is there anything I should know? Looking at the akra manual the diffuser needs to be removed and a cut needs to be made near the bend - is that part necessary? Then undo the clamp in front of the mid cat. Do most people do this with all 4 wheels in the air, I have ramps and axle stands. With the exhaust out of the car, then cut the exhaust 70mm from the lambda sensor weld as per the scorpion fitting instructions.

Also, the exhaust I bought is missing the frontmost clamp, where can I get a replacement?

Cheers, went to a local exhaust place they only had the kind of bar clamps rather than sleeve type clamps so I've ordered a milltek one from eurocarparts.

Fitted using the milltek clamp, worked fine. Scorpion exhaust sounds incredible, YouTube videos I've seen make it sound tinny and crap, but in person there is a bit more bass to it. Loving the burbles and pops it makes.