ELF alteration to vehicles is possible.
Here are excerpts from Motor Vehicles Act (MVA) 1914 / 1939 and 1988. (Courtesy
Cybersteering)
Alteration in Motor Vehicle (Section 52 MVAct)
No vehicle can be altered to an extent that the particulars containing in the registration certificate are no longer accurate.
Before doing any alterations, it is necessary to have permission of the concerned RTO.
After carrying out the alteration, the owner must forward the certificate of registration to the RTO within 14 days, for making necessary corrections.
But will chopping of the roof
alter any particulars in the registration certificate??? That you'll have to figure out.
BTW RTO Thane has a form B.T.I to inform the RTO of these alterations (
http://www.rtothane.org/images/forms/form_bti.pdf)
Good Luck!