Can I put in aftermarket sound in my fiesta 2017 model?

Yes.

What are you wanting to upgrade? Being a 17 plate is it the new shape Fiesta? If it is I wouldnt suggest changing the stereo as you will lose features.

One option - you could just change the front door speakers and perhaps add some sound deadning around the areas they are fitted which would help sound quality and you could carry on using the factory stereo to power them until you got some cash to put a amplifer in. A good amount of amp come with direct speaker inputs these days as not many people want the expense / bother of changing the factory stereo. A plus with keeping the factory stereo is that its not likley to be stolen.

There is a lot of options when talking car audio and it can get silly expensive.

Thanks yes its the new shapes so I can keep the head unit and just add a subwoofer and amplifier and maybe upgrade the speakers at the doors it wil also work?

What unit do you have fitted currently? A lot of the aftermarket units don't have any more features that the high end factory ones dont.

I should mention when I said about not changing the factory stereo as you will loose features I ment things like the heater reading temp etc. I would really look at buying a line driver that you could connect to the speaker outputs from the factory stereo as it will alow you to play with the signal and clean it up before converting to a high voltage RCA output. 

A device like this https://www.audison.eu/products/bit-ten/

You dont need to have a seperate display so the volume is still controled from the factory stereo but you can make all sorts of adjustments via a pc / programe to suit the car and speakers amps you are going to use. I had the above in a company BMW 1series and it really was good.

Reply to Luke 

I changed my stereo in my car as I wanted to have a screen with sat nav etc and as my car is the older shape Fiesta Mk 7 ecoboost it is possible to loose the factory unit without too much hassle. I have an Andriod unit at the moment but after 18months of use its playing about so I have got my eye on a Alpine ine-f904d.

20 minutes ago, Eatonm112 said:

I changed my stereo in my car as I wanted to have a screen with sat nav etc and as my car is the older shape Fiesta Mk 7 ecoboost it is possible to loose the factory unit without too much hassle. I have an Andriod unit at the moment but after 18months of use its playing about so I have got my eye on a Alpine ine-f904d.

The mk7 is a little different as it only has SYNC 1. Unfortunately the problem with the mk7 is the aftermarket units look ridiculously ugly due to the dash layout.

The touchscreen unit in the mk8 is already pretty loaded and the B&O makes for a decent sound if you set it up correctly.

You're talking mega money to go aftermarket to improve sound quality.

You are so right about the Mk7 dash its ugly then if you change the stereo its even worse. I am in the process of re making my whole dash to fit the new radio in the end it will look similar ish to the Mk8 apart from pods each side for my front stage ( Mid and Tweeter) 

Going aftermarket is really expensive its something I have always been into so it is hard to give up. As cars become more and more complicated it gets much harder to change stereo and I think my Fiesta will be the last car I will do this too.