hi all, pinched the following from SCN, who pinched it from Audi-world, might be of interest to some of the techies aplologies if its been posted before

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This is from a post on Audi-sport that I am sure many of you would find interesting of a question sent to Borgwarner who make the K0 series of turbo's

The Question

Can the K03 turbo (5303 988 0011 or 5303 988 0053) be directly replaced by the K03S (5303 988 0052 or 5303 988 0026) in terms of the intake and exhaust housing dimensions?

Is K03S the correct designation for the latter turbo mentioned above?

Obviously if a K03S was fitted an engine map could be changed to suit, but would a standard turbo map for the K03 be suitable for running a K03S on?

or would a loss of power be expected? and are the characteristics of the two very similar?

I hope you can assist with the above and any information you could supply would be gratefully accepted.

It's taken me a couple of weeks to get a response, but the response was well worth it, I think y

interesting theory....

have been speaking with AET-TURBOs (borg Warners uk reps)

they gave me the same offical line....

but then said they were aware of the name k03 sport but it was not a "factory term" equally they were also aware that the factory numbers were a little conservative and were very much dependent on the spec of the block / head they were working with.

The actual diff between a K03 sport and a K04 is a little bit more than the factory suggest but you will have to make other mods to realise it.

Thanks for that, Paul. So which of the above turbos equates to:

06A 145 704L fitted to the AGU (and 99/00 ARX).

06A 145 713D fitted to the AUQ, AUM, ARX.