what is better a regina or bosch system on a volvo?
 

I have a Regina.

Neither is better, they are just different and Regina is more expensive... Also parts people will not know about it and offer you Bosch, so keep that in mind.

What Lev said ^^^. Certain Regina specific parts are particularly more expensive. The coil in particular. Some Bosch parts can be substituted, for instance the fuel pressure regulator. Regina uses a 2.5 bar fpr while the Bosch uses a 3.0 bar. I've used a Bosch with no issue. As far as unmodded daily drivers, both are nearly bullet proof systems. The only real issue is for those few people wanting to turbo a Regina car without swapping the entire motor and injection system. There were no turbo Reginas so no ecu's with turbo fuel maps exist. There have been some turbo conversions; I believe those folks went with after market systems such as MSnS for fuel/spark management. Also, I believe there were no manual transmission Reginas.