Indeed.
The standard Monza that is offered by most people is mild steel.
For me that was the reason not to buy one at that price to be honest.
A stainless steel version is available too, but that will set you back over £1,100.
For that sort of money, I would personally go for a custom system.
Have a look at TMC Motorsports (also a forum member) they have good performance kits (add on box, instead of remap).