I have an 02 4.4 and it's pretty fast. I'm the first one to make something go faster but this is quick enough, trust me I drive fast.

I was watching a show...5th Gear I think and they were doing things to the AVERAGE used car to get more power...each thing they did they would go to a dyno. They did all the bolt on cheap stuff.

The largest HP gain was running a can of fuel injector cleaner in one tank of fuel. Netted back something like 8-10 or more RWHP it lost. I know it sounds funny but try that first. My 4.4 is a REAL fast off the line and top end. Your not going to beat a new Corvette but it's probably faster than 90% of the non blown stock street cars on the road.

Bav Auto sells things like hotter coils and wires they claim boost torque and HP but don't say how much. Same with cold air intake, exhaust ect.

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2002 X5 4.4i Sport Wheels
2014 X5 35i M Appearance & suspension package
1995 Porsche 993
1972 Porsche 914-6
2020 GLE 450 Twin Turbo
2019 Alfa Stelvio 500hp Quadrifogilo
Many motorcycles