Question about CC shield: do I also need custom locking bolts?

Do a search as there are numerous posts and threads, here are a couple that might get you up to speed..

Preventing Catalytic Converter theft | PriusChat (would go expanded metal, or with the rebar option, or both)

Catalytic Convertor Stolen Even with Cat Shield | PriusChat

 

If possible, store it in a safe place to sell in the future, as it will increase in value as time marches on.

 

If somebody jacks your car up, throws out some lookouts or a block car, and slides underneath with a pipe cutter, they're gonna take the cat regardless of whether or not it's an OEM unit. Especially at night and if they're in a hurry.

So....I would only sell the OEM cat if it were worth more (real world) than the time and parts it would take for you to source and install an aftermarket replacement, otherwise the juice just isn't going to be worth all the squeezing.

If you already have the cat shield it won't hurt to put it on.
It's like a speed bump.
It won't stop every thief, or maybe even very many of them, but it will slow down the less determined.

I do not think that it will matter in the end what type of fasteners you use....because the would-be thief isn't going to burn a bunch of clock sitting there unscrewing them.
They're already practiced up and know where to cut the cat shield, or they will move on to the next victim.
Besides.....unless you use something like SS rivets the only person who is going to have a hard time removing the fasteners is somebody who doesn't have anything faster than dial-up internet.

SO....If you insist on staying in Portland with a G2, (it was a fantastic city 20 years ago!!) I would diy install the shield with whatever fasteners they shipped it with and save up for a replacement cat.
Since you live in a place that (shockingly!) actually allows people to replace stolen cats with aftermarket units, your loss is limited to about $200-$400 per theft.

That ain't nothing, but it's not worth hiring 24-hour security or lying awake at night worrying about.

If you decide to sell the cat shield to somebody who lives behind the tinsel curtain, this site had a "For-Sale" forum.

Good Luck!!

 

No need for custom bolts. Just fill the socket heads with putty or sealant. That makes them tedious and time consuming to dig out with a micro blade screwdriver.

However, nothing is impervious to the battery powered angle grinder with an abrasive cutoff wheel. Angling the edge will grind off any fastener in a few seconds.

Then, again, it can be used to cut off the exhaust pipe, too.

I do paint the exhaust system including the cat with orange VHT paint and put yellow "catalytic converter engraved" stickers in the windows.

A thief will almost always shine a flashlight under the car and look. Just seeing the exhaust painted orange might make him or her think of going elsewhere.

 

That was me not being clear.
SS for 'stainless steel' as opposed to some of the aluminum 'pop rivets' that some people use.
As @Georgina Rudkus mentioned, you can just fill whatever fasteners you get with the shield in to make them harder to back out.
Layered defense - or "defense in depth" if you want to get fancy.

 

Aluminum rivets are easily drilled out with a high speed steel drill bit on a battery powered drill, since the bit easily "bites" into the soft metal.

Stainless steel is hard to drill and if it bites at all, the there is not enough friction between the rivet and the holes to keep the rivet from spinning in the holes. Adding a closely fitted stainless steel washer increases the likelihood of the spinning.