Does GM claim any noise level on stock exhaust?
04-12-2012, 10:56 AM
#21
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Sound pressure level varies like square of distance and
there should be strictly defined test conditions (like, in
an echo-chamber shop bay is probably not legit). You'd
have to drill into the local law and referenced methods
to see about that, and compare to the shop's test
conditions (distance, "weighting", enclosure / proximity
to reflecting walls, etc.) and challenge them on any
discrepancy. Sniffer operators are not necessarily
acoustical engineers.
My recommendation is to do some kind of exhaust mod
that can be easily undone right after inspection (like,
a flanged section of I-pipe that can be replaced with
an identical appearing, internally muffled one - stuff
it with stainless steel scrubbing pads, or whatever.
My Harley has little inserts in the back end of the
pipes, that take it down from totally obnoxious to
simply loud.
there should be strictly defined test conditions (like, in
an echo-chamber shop bay is probably not legit). You'd
have to drill into the local law and referenced methods
to see about that, and compare to the shop's test
conditions (distance, "weighting", enclosure / proximity
to reflecting walls, etc.) and challenge them on any
discrepancy. Sniffer operators are not necessarily
acoustical engineers.
My recommendation is to do some kind of exhaust mod
that can be easily undone right after inspection (like,
a flanged section of I-pipe that can be replaced with
an identical appearing, internally muffled one - stuff
it with stainless steel scrubbing pads, or whatever.
My Harley has little inserts in the back end of the
pipes, that take it down from totally obnoxious to
simply loud.
04-13-2012, 03:28 AM
#22
Yes I'm absolutely able to quieten it down a bit. A do this every time on my Silvia, but it has 1 exhaust exit, easy to fill it up with smth.
But here it is Magnaflow muffler with 2 exits, so 2 times more work. I just find it ridiculous that my LS1 must make no more noise than 2.0 econobox. Apparently GM made exhaust legal for 95dB, but here it is only 85dB which is 10 TIMES QUIETER.
But here it is Magnaflow muffler with 2 exits, so 2 times more work. I just find it ridiculous that my LS1 must make no more noise than 2.0 econobox. Apparently GM made exhaust legal for 95dB, but here it is only 85dB which is 10 TIMES QUIETER.
