As i said side coils needed alteration.head on coils can be swapped easily by any one bt as i mentioned that side coils grip had 4 wires while head on engine coils just had 3 wires on its grips.so mod was needed plus extra wire was also used.
Got this mod done today
One change i noticed immediately is low pickup
But car is no more backfiring...headon coils lag jaten bt phir max 6mnths chal kar kharab hojaten
Tappets adjustment,plugs cleaning are also included in that 1000 rupees labour