Im not a Karachi Brother, but my first cousin went to PNEC for his Electrical Engineering, as a NUST student. He lived there for 4 years, off campus, with his mother. The area around PNEC (Karsaz) is very safe, navy owned, and good. Accomodation is easily available. My cousin had a very good experience there, and has since moved to Lahore, but still remembers Karachi very fondly. You will have a great time there as a student.
Was your cousin from Lahore or Punjab? From where he completed his FSc or A LEVELS etc. Where he found accomodation-- flat , rented house or what. Had he relatives in khi. Please please do reply. I am particularly excited to ask these things as your cousin's case is just the same as mine. My mother is also destined to accomany me there in Karachi.