I guess it depends what you consider performance mods...
eg:
on a PD130 without a FMIC, in the summer, especially with a remap, your car will heatsoak like a mofo...with a FMIC it'll be consistently good 365 days a year.
PD150 and PD160 have adaquete FMIC as standard.
Therefore I'd consider an good IC as one of my top 5 performance mods. (OE PD150 or PD160 ICs worth getting)
Secondly, if you can't go round corners quickly, there is little point having lots of power, as we're not in america.
So a set of coilovers (£525 for KW Variant 1s or £575 for V2...) would be factored in.
Thirdly, if you can't stop, then you're likely going to die...
Ibiza Cupra PD160 has AP Racing 4port calipers with 312mm disks...Leon Cupra PD150, Leon PD130,
Ibiza FR PD130 all have 288mm disks with singlepot calipers....they need at a minimum an upgrade to the 312mm disks and calipers from a Leon Cupra 1.8T, or ideally Brembos or AP.
Fourthly; Now your car is cool running, can stop well and go round corners, I'd look at a remap...revo have dealers nationwide, which is great for lazy people, and their code is smooth, and gives good results.
Fifthly; improve the breathing of the engine. This is split into two... (1) intake (panel filter usually enough for a TDi) (2) exhaust (milltek with race cat the way to go.)
The above will give you pretty much where my car is now (FMIC, Revo, Milltek, KW V2, Brembos, dynatwist)....
beyond that ... there are bigger/hybrid turbo conversions available, and bigger injectors, but economy of the car will go down a fair bit after such work, and the potential for increased lag from the turbo may put some off.
or you could go the JBS recommended path and get their NOS conversion, which gives good results.
You'll want that SACHS uprated clutch though!
