The top and bottom of the cats flanges are threaded only the middle is none threaded.. as you can see in the Pic.
http://images53.fotki.com/v444/photo...SCF0503-vi.jpg

which is driver's side?

The one closes. The cat in the background is the Passenger side, and has the same bolt pattern.

These are the best shots i could take for the passenger side

Top Left, the evil rounded bolt
http://www.the370z.com/members/g9681...-left-bolt.jpg

Bottom
http://www.the370z.com/members/g9681...ottom-bolt.jpg

Top Right
http://www.the370z.com/members/g9681...right-bolt.jpg

driver's side is mirror image, i guess the manual is wrong?

Funny,..the bolt that rounded on me is only the top one in your pics,..but on the driver side..

The rest I got off easier cause I had access to it underneath. The problem with the top bolt is that your socket doesnt fit over it perfectly on the driver side since its down at an angle... I did use a lot of PB blast and even let it soak overnight before spraying again the next day when I tried to do the install. Let me know if you are going to tackle this again and I can try to help to get the top bolt off if you use the 2 person method. That is, one to hold the extentions in place and the other to torque it off using a long breaker bar/hydraulic jack handle...

^^ only the top one rounded for me, the rest came off, just kinda pointing out that either the manual is wrong or nissan installed mines wrong.

i also used the impact method to no avail, gonna try the remove the front tire method that someone mentioned.

wow dood that sucks that it rounded off... try slamming in a tight 12point on the rounded bolt and keep slamming it the shock of you slamming it probably will knock it loose :tup: then pray to god the 12 point has a good enough grip and try loosening it.... dont use the impact when u do this itll just round off the bolt more... when i did my stillens... i almost rounded off the bolt.... luckily it gave out b4 it did... these bolts are a pain in the f*ckin ***... i can only imagine the headers...

if all else fails, remove the headers. i hope it doesn't come to that

yah.... thats what will suck the most bro.. ill keep my fingers crossed for you

thx, gonna try again this weekend if i have time.

If you can,..can you take pictures to document how you are getting it off since the bolt rounded off..

This would help DIY'ers if this should happen, and that includes me...

I think you mentioned that you are going to take the wheel liner off on the passenger side? Pics of that and how you worked (are working) to get it off would be worth it us all...

Hellm if there is enough room after taking off the driver side liner in the wheel well, I would take some kind of wheel cutter, or dremel cutter to cut the nut / bolt off.....that would save getting a hernia and bloodied knuckles...

i'll try, no promises though, but not this weekend cuz i just found out i gotta work

LMAO, damn.. Impact Sockets are very strong too..

You guys with all this rounding really need to make sure that your socket is fully seated on the bolt. I sprayed my bolts with PB Blaster every night for a week before hand and then just before removing the cats. I used an impact swivel and an impact socket and while it wasn't easy everything did come off with no damage at all.

Here's the main thing. Make sure you do all you can to ensure you have the perfect angle before even starting to crank on the ratchet or breaker bar.

I think for those that have this problem, already missed the point...
Will try a swivel elbow and socket and try again at a later time.