The thing is that, When you remove the dholki and fit a pipe it increases sound,
You remove the dholki, break the catalyst, weld it back, (leaved hollow space in side) creates sound and a shrill sound
Best way it to find a replacment (jalli wali) that keep the sound orignal, But for that cut and weld is required which atleast i hate, rewelding always leaks. and makes problems very often.
Im happy with my car doing 12km/L now, if it goes below 11 or 10, then i might consider removing the cat for now im happy.