Not sure how you were able to get to reach without extensions, but both my car and a friends, there was no way in hell the factory ones were going to reach without the extensions. Both of us running Stainless works products.
Have to unscrew nut from bolt and the back side of the bolt is held in by a clip. Much easier to remove while headers are out. Stainless Works/Power instructions do reference the removal. Unsure how to remove with headers in car... Remove battery box and try and reach that way? May need to shift...
Apparently nobody reads the several threads about this exhaust having drone, yet still purchases to find out...It Drones. It's a race exhaust. Try and weld in some resonators and see if it helps.
I am going to check mine out soon as well. Did you have any issues getting to the spark plug closest to the battery? Did you have to remove the battery box?
I just ordered the Velossa Tech big mouth hoping it helps keep the IAT's closer to ambient and recover faster. I've already opened up the airbox and the MAF is angled down inside the box to help out as much as possible. Crossing fingers the big mouth helps.