Need to quiet down a streetported 1987-1989 13B.

Anyone running a Flowmaster? Is it quiet? Holding up?

 

Dont know about the rotary but chambered mufflers (flowmaster) are for sound, not really performance. Its there to do its job, to "muffle" the sound.

The v8 guys use flowmaster when they still want sound yet not too much sound and not really care about max gain with exhaust mod.

You should just look into racing beat. They are amongst the quietness of all exhausts, for both fc and fd.

 

I've tried them on a couple different cars. The biggest issue is the design, not how much it flows. On my flowbench they move more than enough air to do the job without killing power. The issue that only shows up on the dyno is that the engine "thinks" the exhaust ends right at the front edge of the muffler where the pipe enters. If that length works for your porting, you're fine, if not you are giving up power. Look up the term Helmholz resonance.

On an old IT car, we picked up about 5hp getting rid of a flowmaster and putting on a dynomax. I liked the sound of the flowmaster, more like the old GTU cars than the big chainsaw for a street car.