Custom xipe help- exhaust expert advice needed

[nvdave04]

Monday can't get here fast enough lol question to exhaust experts - I recently added a custom 2.5 inch xpipe with no resonators to a nismo muffler and rasp is crazy ! I also have berks HFC. When car was on the lift we removed all heat shields and checked all bolts and did not help btw I noticed all the rasp was coming from the xpipe. So I will be adding some resonators The tech thinks something inside the nismo muffler came lose and that's the issue so I purchased a new Topspeed axle back

So the ? Is
Since all the rasp is coming from the xpipe in middle of exhaust where should I add the 2 resonators ?? Before or after the xpipe and do you think 2 packed 10inch resonators are good or should I do bigger ones - once again this is going to the Topspeed axleback with 2.5 inch mandrel bent pipes..

Also the tech did not add any flex pipes do you think adding those would help wand if so where should I add ?

The rasp is so bad I don't want to drive my z anymore so any help I would appreciate it.

Thanks