I have 1997 850 N/A and i modified the stock air intake box with a k&n filter. I removed all of the plastic that was in front of the air intake above the radiator. You know the hose that goes over to the exhuast manifold, disconect that from the manifold and stick it straight back towards the passenger compartment and then down as far as you can push it. Mines almost a foot from the ground. Then take out the air box and slide out the part that goes into the air box that switches back and forth from air from above radiator to exhuast manifold, rip all of that stuff out that opens and closes it. I was suprised to see how much this stuff clogged up the intake. The thing was designed for quicker engine heat up but even without it during the winter in kansas when it was 10 degrees F my car warmed up in maybe 3-5minutes and stayed warm the whole time. With those couple of mods I found my car to be alot more responsive off the line and high up, I can take my friends 325is off the line and up to 50mph and i can take my friends 89 740 turbo. If you want pictures of the mods just ask and leave your email address. I also added a front strut bar from eastern aerospace that tightened the front end up quit a bit. I can take most of the little ricers too. We took a civic with nos in my friends 740 turbo and when we beat him and slowed down he pulled up next to us and says "Damn that's one mean volvo!" in this almost frightened voice, it was one of the funniest things i have ever heard in my life.