PDT did an excellent post which explained this, maybe he'll be able to find it and repost it.
This is something I posted a while back, not directed towards any tuning company in paticular, but gives a fair perspective of cheap remaps:
Only you can answer the question that you really want answered, "is it worth trying to save £200 and take a risk"
The chances are that the remap will work fine, but you will always have a niggle in the back of your mind asking is what you have as good as REVO/GIAC/ or a properly tuned custom map from a pro tuning company.
The company you have mentioned, I know nothing about so I can comment but just by looking at the front page of their website its clear that they have no dyno to use to develp their files and that they buy their files from a 3rd party and get them sent by Email. The question you must then ask is not wether the company that you are dealing with is any good, but if the people they buy their files from are any good, and wether they have been professionally developed and tested, and if the file writer and the reseller can both make profit out of the £211 (249 minus the VAT) after covering their costs?
I say it may be worth trying, but make sure you log your car afterwards with VCDS and look at blocks 115 and 20. This will tell you if the ignition is advancing correctly and you will see the boost levels that have been 'mapped in' then check the EGT (exhaust gas temsp) and the AFR (air-fuel ratios) are ok under load then check block 4 (intake air temp) after a few runs and see if the boost level is adequate for the intercooler, anything above 45 degrees is getting too hot.
^^^all of the above would have been done by a REVO dealer or a mapper that cares about their customers cars long term reliability, is this included in your £249 remap? doubt it."
