I was wondering, If buying a used car, is there anything to look for to see if the car had previously been running nitrous?

I'm asking because a friend of mine bought a used 99 prelude, and thinks the previous owner may have ran nitrous, are there things to look for to tell for sure?
We did a tune up on his car, and the old spark plugs were ZEX, which from what i understood are commonly used in a nitrous setup.

 

other thne holes in the intake and holes in the floorboards to run the lines. Not really.

 

Check if the TPS wires have been tampered with.

 

Can't you check the welds around the intake manifold!!!!!! (FnF)

 

you should be able to tell. THe bottle had to mounted some where so holes must have been left. Maybe a cut vac line for the fpr, but that can easily be replaced. Check to see if the original fuel line is still intact. I'm sure there's other things.

 

honestly what does it matter if the car runs good and the motor is in good shape?

 

do a leakdown test. If it turns up good then either way it doesn`t matter. Other than holes for the lines, tapping, and blowdown tube it would be hard to tell. You could always ask the previous owner

 

nahh theres soo many ways of hooking up nos... looking for holes in the intake mani will be useless if the guy didnt even run a direct port setup... and lookin for holes on the intake arm for single fogger could be uselsss to cuz all they gotta do is swap up the intake... and the solenoids and fuel and all that ****.... they can just get new fuel lines.