Due to the sound sensor fitted to phones they aren't accurate beyond about 90db, above that they're basically useless for anything else than determining which of 2 noises is louder.

You can get cheap sound meters from Jaycar that are fairly accurate.

 

Cheap Jaycar Micro sound meter $39-95

Better Jaycar Compact sound meter  $99-95

Semi-pro Jaycar sound meter with calibrator (class 2 compliant) $399-00 

 

www.jaycar.com.au

 

My app stops at 90. But I think im louder than that so I cant help.

Sound meters are a precision instrument used to measure Sound Pressure Levels. I definitely wouldn't trust a 3rd party software application on a "smart phone" if a sizeable fine from the EPA could be the result from a failed test. I've been for 3 enforced sound tests and they told me that if it's not a stock exhaust, it's probably too loud. Unless, of course, you heavily baffle your non-standard pipes and the tester doens't ping you for modifying the exhaust.

Safest bet, put your stock-o's back on.

^ What Hooky said, if you want to pass the EPA you need the stock exhausts.