the LRD silencer i have coupled to my F7 pipe is way quieter than the other way around, i have an F7 silencer coupled to an LRD pipe on my sons
don't ask why, hahahaa,
thats how my exhaust came, and my sons had a complete F7, but i got a better looking LRD pipe for his, and just kept the beat up F7 silencer on his
but his is loud as fug, even with a basically stock motor, versus my ken oconnor built powerplant/LRD silenced
i also think fmf makes a quiet series, not sure what its called though