Exhaust db levels?

[winnacott]

Have any of you out there had a db reading at a trackday with a exhaust with a decat and straight through middle section,if so what was it!!?and is there alot of difference between an unsilenced or silenced middle section or is it the decat that makes most of the difference in the sound levels..cheers!

 

[Kam.]

probably looking at around 10db quieter for a mid silencer as a rough rule of thumb

 

[Ian_s]

Janspeed with centre silencer and cat - 78dbs (tester said it sounded like a sewing machine)
Janspeed with centre silencer and decat - 85/86/87 depending on which track/tester

The cat makes a fair difference to the noise.