Does anyone know how to install this rear diffuser

 

3M double sided tape... if that worries you too much use a couple screws above the exhaust...

 

so i just use the double sided tape it came with to stick it up to the bumper? or how does it go on there...sorry just curioius cuz i dont wanna screw it up

 

By your post,I'm assuming you have not done any installing of body mods?
As has been already recommended,use 3-M double sided tape.I strongly recommend using adhesion promoter prior to mounting the diffuser.Make sure all surfaces are clean.Use
rubbing alcohol.Since we are in cold weather,use a hairdryer to heat up the tape a bit before mounting.More than likely the diffuser will not mount completely flush.In those areas(usually in the part under the car towards the front),use screws to get a good seal.I'd use some small head S/S screws with "security"
hex-heads painted black if the diffuser is CF.