In my former life (with a WRX) I messed around with boost controllers as a inexpensive method for increasing boost a few pounds safely.

However in my year of owing my 02 T5 I have never heard of everyone using a boost controller on a Volvo...is that because everything is so computer driven?

I want to do an ECU reflash but will have to wait for some funds as those are a bit more expensive than the boost controller

 

The S60 does not like a boost controller. It is all computer controlled.

 

You can try. But since your a 1999+ car with ME7 it may not work at all or work right.

Just do the ECU upgrade like you stated and you'll be happy.