Is he the person paying the car payment? Buying the mods? Driving the car?
Then does his opinion really matter?? Didn't think so.
No, the VQ37 is not very giving when it comes to bolt ons and extra power. Yes, the parts are relatively costly, but quality comes at a price. Fast Intentions doesn't charge what they do just because. They do because every exhaust, HFC, TP, LTH, and coming soon a TT kit, are all handmade in house. Some parts are brought in from outside sources, but the end result that's shipped to you is all of their creation. You get what you pay for. The same can be said for some of Stillens products.
It basically boils down to, if it makes YOU the owner/driver of the car happy, then that's all that matters. If this guy wants to complain, then let him complain, in his own car. You do what makes you happy with yours. Remember, mods don't only give you power gains, typically, they also look far better than stock, and especially when it comes to exhausts, sound better too.