Bro i think u shud take the challenge and go for it . the reason is that ur car is 1500 hence has more torque too, apart from the 10hp extra power.and urs is atleast 40kg lighter then his plus his car wud be in the "Running" period and i ve noticed that cars usually dont run as fast in that period as they do after 10,000kms or so.and if ur 50,000kms very driven with care, that wont reduce even 1 hp
as for the catalystic converter, i got my cars' opened cuz it was broken inside due to a bad hit.my car had done 20,000kms on petrol and converted to cng after that, but i do drive on petrol very often so lets say it was 30,000kms driven on petrol, but i cudnt see even small amount of choking stuff in it.it was completely open and wud be as gud as new.so dont worry about it.
Also let me explain that there are two types of CATs usually used in cars.one is ceramic based, like in city and other low priced cars and other is platinum based which is used where pollution rules are strict, even imported vitz has platinum ones i think.the latter one is more effected leaded fuel, which we get in pakistan. so we dont need to worry about choking CATs...