I've a Civic 2005 Exi, which i purchased recently. It had CNG on, briefly, before i purchased it and had it removed. It's mileage is 53000, the problem is that when I drove it on the motorway i felt slight vibrations around 110 kph, which reminded of my cultus when it's tuning was out.
The second problem is that it achieved a speed of 120kph on around 3800 rpm, which i think is quiet a lot considering that even a cultus does 120 on 3300 or so.
So my question is what exactly could be the issue with it? Is it the tuning/teppet adjustment or what?