No

What are the downsides to running the turboguard with the filterwear compared to running the intake system?

From what I’ve gathered, people usually don’t recommend running a turboguard on a daily driver

It entirely depends and is completely subjective as everyone is going to have their own opinions on this. On a daily I would say yeah you probably should be running a filter. Theoretically running without a filter certain particles ingested into the engine can begin to wear the piston rings/cylinder walls.

Personally I don't run a filter (anymore) but my Z isn't my only vehicle and I don't daily it. On top of that making double the power than stock I don't exactly expect my engine to last 100k+ miles where it'd matter anyways.

I'm really surprised whatever intake they made for you was so restrictive that you only managed to get 5psi out of it. I'd be curious if you had some pictures of it. I had a shop at one time try to make me an intake and they did an awful job with a very obviously restrictive "box" that the airflow had to take several 90 degree turns, and even with that I was around 9psi.

The filterwears is a really fine cloth mesh screen that goes over the turboguard. They work really well to even keep most dust particles out. The downside is that they're restrictive but it can be removed in a second. Great to run as a daily and if you're in a situation where you want a few more psi, it only takes a second to remove it. It's held on with elastic and stretches over the turboguard