[Toxic0n]

I don't know about the M3 but in my 328i the rear strut bar made zero difference. It looked cool though

[john mason]

Originally Posted by PerkM3

From what I've seen/read theirs is the best.

If you can keep the rolling box =[chassis] in square, whilst under G loading
the proper/correct suspension settings can be maintained
resulting = better car control,tire footprint,braking,etc
BMW stamped steel spot welded chassis does flex/wiggle under load
tower bars front and rear and lower do help to direct proper load paths
preventing suspension hard pick up point/node failure

[ndyvidual]

Thanks everyone for the useful information. If I can find a bar with a removable section that's cheap, I will get one to complement I get the upcoming coilovers.

Otherwise, I will just get reinforced mounts.

[IHatePosers]

unless its welded onto the rear shock towers and the subframe, it will do absolutely nothing

[ndyvidual]

Interesting statement IHatePosers, so would this theory also apply to the front OEM bar?

[mpanella]

I think the rear deck would start cracking before that bar even got any weight to it. I mean think about it they would have to make it a extremely tight fit like perfect for it to help at all in that section.

[ndyvidual]

I agree and that was one of my motivations to ask the forum. If I had a convertible...maybe. Not sure if the shell of a coupe would flex that much, but I've not owned one and want to make sure I don't if there's not clear added value for my goal of better handling.

[mksnwbrd8]

I don't see it doing that much since the springs are mounted in a different spot and thats where most of the forces are applied

[mpanella]

And your sub frame would take a dump even before it flexed that much

If it needed it im sure M Technik would have added it to the design. Like the 350z has one built in.

[turbo_f22_pilot]

A rear strut bar will make a difference in the handling of the vehicle. But the ability to notice the change is based on your driving style and the type of driving. The suspension mods also affect how much rear strut bar's stiffening is noticed.

As for AUTOX, it depends on driving style. Some people like to have the rear of car rotate quickly. Some don't. The strut bars for our cars is to keep the shock towers from flexing. (in most cases collapsing in under load)

Originally Posted by mpanella

And your sub frame would take a dump even before it flexed that much

If it needed it im sure M Technik would have added it to the design. Like the 350z has one built in.

Not necessarily true. It might have been left out so that the normal owner could use their trunk. A lot of cars don't come with them but can have their handling improved with their addition.