Hey people I am new here. I bought a 2014 Ford Fiesta 1.25 82 PS from a reputable garage (Bristol Street) and have had it almost 3 months it has 15K miles on the clock and has been problem free until yesterday when I heard a pop could not tell if it was from the engine or tyres but on checking the tyres they were fine, so decided to continue on my journey home but it was slow going I could not get the car above 60mph on the motorway and I also got my dad to check the tyres and he said they were fine. It is still under warrant until the 23/05/2017. Any idea what this could be? My first thoughts were the syncro or the spark plugs but a car bought from a reputable dealer like Bristol Street Motors. I dunno either way I am worried. 

I would take it back to them as your warrantee end on  the 23/05/2017

sounds like the cat is making it bog down no power