Did some searches as I'd almost be completely sure someone has had this issue before, but nothing came up.

I have done a Warpspeed Y-Pipe and a oversized chrome fart can on my wifes car (she likes it loud) but the thing I notice is it's really loud inside the car and not outside the car.

The idle sounds great.. quite lumpy like a Subaru WRX or something, but around 2,500 rpm it drones and reverberates through the car like an instant migraine.

Has anyone done anything with sound deadening inside the car/boot? I'd rather hear the exhaust making heaps of noise outside the car instead of inside.

I had another Maxima previously which had the same issue. Loud inside and not out. I have driven a Nissan Skyline which was obnoxiously loud outside and not inside.. i'm wondering what I can do to get it to be like that.

Any suggestions/links?

 

Change the exhaust. Add a resonator.

 

you can add some dynamat to the inside of the trunk to make it quiet