Every tuning part, INCLUDING a power box DOES affect the turbo...
A diesel is great to tune and get about 30 to 40bhp an about 100Nm torque because of tuning the turbo... If the turbo wouldn't be affected, you would NEVER get these results!!
I drive a 525tdsA Touring from 1992 and mine will be proffesionally chipped at the end of this year. This will be done by 1 of the best tuners here in Holland.
www.boltuning.nl Believe me... He knows what he is doing...
I'm now looking for possibilies about building an open air system...
also am I looking for the possibilitie to make it a bi-turbo... IF that's gonna work, I will get about 240bhp and about 550Nm...
BTW... The turbo of a M51D25T and the M51D25TU (325/525td and 325/525tds) are the same... the only difference is the intercooler and computer...