Not that it backfires but you will hear it ping when you lug the motor down low. An easy way is to have it in 5th gear cruising at 1000 or 1200 rpm and give it a good amount of gas. If it pings it usually to me sounds like marbles inside of a metal can. Or you can try going WOT and see if it starts to ping but the first option is safer.
2016 VW GTI 2.0 Turbo
1989 Sonic Blue LX Coupe, 349 ci, TW heads, TFS Track Heat Intake, 75mm Accufab TB, 80mm ProM, 30 lb. inj, TKO, 3.73, 31 spline w/ TruTrac, MAC 1-5/8" LT headers w/ H pipe, Flowmaster, electric fan Moates QH
391 rwhp & 424 rwtq...Mustang Dyno 11.5@122mph