The supplier named in your post says it all. They don't make the pipes, but as an observation, appear deaf to the ears of their trade customers and end users. The same problems continue to appear.
No surprise here, the pipes from any of the major factors rarely fit first time.
Are they the correct pipes? Plunger mounting bracket "plunges DOWN", S/A pipes bracket points "UP"
The problem can be two possibles. One will be in the sweep of the header. This will be impossible to bend to correct without damage using backyard technology. Second possible is simply the bracket is in the wrong place.
Easy solution is to forget the lower front mounting bracket, see how the pipe lies, then adapt or amend the bracket for the best compromise. Any amendment here is less noticeable, and in fact may only require minor adjustment, as any error here in misalignment is magnified as it reaches the silencer. The pipes should be a straight run to the silencer. S/A pipes have slight kink on the drive side pipe. Plunger pipe runs very close to the back of the brake pedal, silencer front end is very, very close to the frame, a gnat's knacker dimension.
If they are too bad, then Kiwi's way is the next step. Surgery and/or major force. Avoid any force on the ports. Pipes are cheaper than cylinder heads.
Swarfy.