common problems of conversion to CNG
major problem is always about idling adjustment. if improper adjustments are made and car is forced to run lik ethis, then backfiring can cause damage to air cleaner box.
remedy is to make a habit of changing to first gear whenever speed drops below 15 km/hr. Proper adjustment of CNG is a must.
Also an expereinced person who know about the electricals of spectra can do a better job of installing emulator and advancer.
Once the job is done in a proper way and u r accustomed to CNG driving habbits, no major problems are likely to arise apart from routine maintenance and adjustments.