What effect would it have on my internet connection if I upgraded my upload speed from 1.3mb/s to 2.5mb/s (about 256kb/s)?

[dsmartuk]

At the moment I have 20meg ADSL internet connection and I get speeds of 15mb/s (1.6mb download), 1.3mb/s (120kb upload)

[AlBags]

Practically nothing in terms of browsing & streaming. Download of data .. very minor.

[ChuckFickens]

For a start you are confusing/swapping units about you can have megaBITS a second which is written as Mb/s (note small b) or megaBYTES a second, which is written as MB/s (note large B) so your connection speed is 15Mb/s which gives you a download speed of 1.6MB/s and the upload speed is 1.3 Mb/s which equals about 120KB/s

Now to the actual question. (and I think Al might have misread the question)

Upgrading your UPLOAD speed is going to make virtually no difference to you using the Internet unless you spend a lot of time uploading things to the Internet, or if you are trying to run some sort of server from your home connection that people outside your house are trying to access. for normal day to day use where you are almost always downloading from the Internet upgrading your upload speed won't be noticeable at all.

[AlBags]

I did understand .. but time constraints kept answer brief!
Increase upload usually has an impact on download speed .. although very small when you have that bandwidth available.
I thought he was 'really' talking about downloading tho .. would be noticeable but not a remarkable change, unless downloading large amounts of data..