Exhaust noise
Flow masters "resonance" happens between 1500-3000 rpm. The old "2 chambers" are the worst. My big block El Camino,drove me nuts. I would look at a crossover,and some Ultra Flo's,or Super Turbo's.(both by Walker exhaust). Tried the crossover with the Flowmasters.It raised the resonant point ,higher in rpm. That's all.