Yeah that shit is real. Even if they didn't sign it, you have been issued a defect number which gets entered into their computer back at HQ which is then sent to the RTA.
Pretty much anything on your car which is not stock/original/OEM is defective unless you have an engineering cert to back it up.
It's pretty retarded they got you for the strut brace... did you replace the original with an after market one? If you didn't then you will have no problem getting that cleared.
Which brings me to my next point. There's an easy way or long way around getting this cleared...
If you can find a mechanic that does blueslips and is laidback/not an asshole, he might let you off lightly with your car "as is".
- or -
Getting an engineering cert which costs between 400-$500 and getting everything to complied:
Ensure your exhaust is under 90db. This is measured 1 metre away from your exhaust tip @ 5000rpm.
Passing an emissions IM240 test for having an aftermarket FMIC and Airbox. Pretty much any modification to the induction system warrants an emissions test so just be conscious of this. TIP: Bolt the original airbox back on and convince the engineering assessor your FMIC is "Stock", that way you don't have to get tested.
Strut brace should be fine. Aftermarket or not, make sure they specify it anyways in the engineering report. You're paying good money for them to write the report. That way your certificate will 'trump' any policemen's claims that it's a "defect".
After all is said and done and you have your report, take it to the bluslipper and then to the RTA and show them the report to attach to your registration.