I have the chassis bars... and I think they help.. but do not cure the problem. I was one of the first to write I thought chassis flex was less, but as time has gone by I have grown more suspicious of how much they help. They will not take your cowl shake away.
What no one talks about here, is that none of us are really chassis engineers. And although the type R uses these braces, we don't really know what they do to a targa. The type R is a coupe. It has very different characteristics than a Targa. The bracing may actually transfer load to a less desirable place in the Targa. I am not saying it does, but it is a possibility. I am just warning some caution on making general statements like the R bars eliminate the flex.
Having said all of this, the car with the top on feels as tight to me as a coupe. It probably isn't quite as tight, but it's darn close. There is a big difference once the top goes on.
Anyway, I think its worthwhile to try the chassis bars and make your own judgment, and now there is a front strut bar recently posted. I don't think there are any drawbacks to making the car more rigid.
Was the 04 you drove riding on a stock suspension? I have driven a lot of Targa cars MUCH worse than the NSX. I would not give up the open air for the small bit of extra rigidity.
Enjoy - i bought both the front and lower beams but have yet to install it ... i will let u know how it goes
