Header nuts not fitting
 

So I'm in the middle of a big project on my 370. I have been swapping some parts and it's been apart in my garage for awhile now I just finished injectors and now I'm on headers. I went for short tube headers from z1 motorsports so I could still have cats (berks hf) for emissions. My problem is the middle pipe on the header bottom hole I can't get the nut on the stud. My first thought was to switch the studs to different holes but my block doesn't have extra holes so I'm stuck with the current holes for my studs. My next step is to take off the wrap I put on the headers but I doubt that will be enough room, I haven't done it yet because I had to stop at that point but I'm going to go at it again tomorrow. I just was wondering how other people have installed the z1 headers I saw a video on YouTube that a guy with a 2015 nismo was able to switch the stud holes but as I said I lack those. The nut almost goes on it just needs a hair of space I also thought of switching from the stock top hat nuts to a regular or lock nut but don't know how well that will hold. Also since I can barely slip the nut on the stud I know tightening the nuts will be the bane of my existence because I won't be able to get a socket on it and I will have to go with a wrench or maybe a crows foot. Just looking for any suggestions I'm so desperate for the car to be back in one piece and btw I have 2013 nissan 370z touring manual. Thanks

Just grind off some from the diameter of one of the nuts till it fits.

I didn't really feel like messing up the oem nuts so I ended up just grabbing a regular m10 1.25 nut with a lock washer and got it on fine. Now I just can't seem to line up the driver side headers.

If you have the Z1 polyurethane motor mounts you can adjust one side to tilt the motor to gain some clearance.

Thanks but ya I still have stock motor mounts