so i recently purchased my friends turbo xs 4" downpipe and Invidia N1 race catback

those were the only mods done to his sti it was pretty loud. the N1 race catback is loud to begin with.
but when i put it all on my bugeye it was not as loud as i assumed it would be. i also have a friend running a different downpipe and same catback on his wrx and his car is louder then mine.

why could this set up not be as loud on my car? im so confused by it. the whole reason i purchased this set up was because i wanted it to be loud.

the only mods different that i have is an invidia up pipe.

i doubt this has anything to do with it but ill throw it out there. on his car he cracked piston 4 and there was oil sludge in the downpipe and midpipe. we tried to was it out but im sure there is still a little in there i doubt this has anything to do with how loud the car is.