I sort of feel obliged to respond to this, as I made the swap from a 1.8T to a 115PD
Quite frankly, you'll never get the same pull that makes the GTI so delightful, but I'm guessing that like me, you're thinking economy but still with some oomph!
Now my 115PD is not mapped, but does have a full milltech exhaust with decat and a smooth airbox piper cross panel filter combo. With that, I have seen returns of up to 64mpg (driven like my nan), but consistently getting 550-580 miles to a tank. The car pulls nicely at top end, and cruises nicely in 6th gear aka 'the money saver'
I did want the 130PD, as the general consensus on here, is that it is the best out of the PD engines. The trouble I had, was that when I went to see my 115PD, the spec was irresistible, the mileage was low, with one owner and FVWSH!! I pondered continuing my search for a 130PD (all for about 5seconds)
Yes I've got a little less power (something that can be increased), and yes I HAD smaller brakes (got TT brakes now
) but you get so much more for your money going with the 115 block!
Hope this helps