I have some concerns about both these products. And before I start, I just need to stress that I enjoyed RedLeaders highly comprehensive review, and respect that Red was able to notice an improvement.
Firstly, the UB - like others, I am skeptical of its ability to control torsional stresses (it being a flat-plain plate, rather than a 3-dimensional brace). However, of much greater concern is its potential huge detrimental effect on crash-worthiness in side impacts. We all probably/hopefully know that cars have 'crumple zones' for frontal and rear-end impacts - those being the engine compartment and the boot. Side-impact crumple zones are much more critical, because there is fundamentally much less 'distance' to absorb side impacts before intrusion meets interior passengers.
Arguably, THE most important structure for side-impact crumple zones is the central transmission/exhaust tunnel. This means that on the standard Golf (sans the UB), when a side-impact occurs, if the intrusion reaches the front seat, and still has enough force (or momentum) to continue - the whole seat should remain relatively intact, but move sidewards towards the centre of the car. With the UB fitted, the centre tunnel will be far more resistant to deform as a crumple zone, so the seat itself will deform, and that would highly likely result in a fatal / non-survivable injury to the front seat occupant (shattered pelvis, shattered dislocated hip and femur). What would this train of thought have regarding insurance implications? I accept that Robin has declared this mod, and Greenlight have accepted said mod purely as a stiffening item - but would they, or other 'mod friendly' insurers re-think their acceptance of this UB mod if it becomes known that they reduce the ability of the crumple zone, and actually increase the risk of fatal injury?
I fear that Robin, and possibly others may have either been mis-informed, or maybe made an incorrect assumption - regarding the two OEM 'braces' straddling the tunnel. Those are not 'braces', in terms of providing stiffness to the body shell - they are actually a legally required retaining device . . . . for the exhaust and/or propellor shaft on 4WD/RWD layouts. Basically, if the exhaust or prop shaft snap or somehow become disconnected near the front of the car, these flimsy stuctures retain said broken exhaust/prop shaft, prevent it from dropping onto the road surface, and prevent said items from digging in and 'pole vaulting' the car out of control.
Secondly, the XB - whilst the product itself appears to be a substancial product, designed to resist compressive forces, I think its mounting points within the car body are compromised, and less than ideal. The upper mounts arn't really on a structural part of the bodyshell. OK, they may be near the rear seat back retaining mechanism - but that part of the shell is designed to take possibly around 150kg of force (basically retaining the contents of the luggage compartment). What you are effectively asking the XB to do is to cope with the force from the potential total weight of the vehicle - say upto 1500kg force. As others have stated, if those magnitudes of forces were applied to the XB, it would simply rip out the mounting fixings as though they were attached to wet toilet tissue! Mike Roberts nailed it in the previous post, the Mk5 bodyshell is continuous-bead laser-welded (unlike the pathetic spot welding as found on even the latest Dagenham Dustbins), and also uses better, high-strength steel. This means that structural rigidity is considerably better - between 40 to 60% stiffer when compared to a Mk4 shell.
In summary, as is usual with the vast majority of so-called 'performance products' from America, they create a product (albeit nicely made and aesthetically pleasing) with little if any actual improvement over OEM, and then create ill-informed mis-beliefs we need said products.
ETTO though!
