There are many benefits, to summarise:
- Efficiency improves around 4 MPG on average, in some cases a lot more
- Responsiveness increases
- Reliability improves
- Lag spot on the turbo is removed
- Turbo spools earlier to give you the go when you need it
- stuttering and stammering related to EGR is removed
- Exhaust gas can be "too clean" on the MOT test
These are just a summary, but we have a long detailed thread here which has much more detailed info, I have done it on my CMAX I owned before my current Mondeo (done it on this as well).
For the cost of £5 it makes a world of difference.
My Mondeo would average around 600 miles to the tank when I first got it, after granny driving I got it up to about 700, fitted the EGR blanking plate and the car started to believe I could exceed 1000! I need to note the next tank, but my MPG shot up from 63 to 73, and the general performance of the car is so much more refined.
The only niggle, is that blanking the MK3 engine (I believe is Euro IV) means that you may end up with the EML on, however one of my colleagues on the mod team (Stef123) I believe just ignored the light and after a while it went away