I have replaced the tired, worn out OEM rubber bushes in "a couple" of MR2's in my time.  It is, IMHO, the single most economical improvement that you can make to the ride and handling of your car.  Most economic in that unless you are getting a very special discount the cost of the complete poly bush kit is less than you would pay for Toyota genuine rubber.  And don't even think about non-genuine rubber, it's been my experience that you would be replacing it in a much shorter time frame anyway.
 
As per my earlier comment, NVH from the Two'sRUs kit is not significantly different to new factory bushings. What usually complicates the harshness story is owners who combine a bush replacement with an aftermarket strut/damper replacement.  Following on from Maj's post about squeaky, this usually comes from incorrect fitment.  Lubrication is very important.

I have an Aus delivered AW11 which I am endeavouring to keep in as original condition as possible.  I have replaced all the bushings with urethane bushes from TwosRUs.  The kit didn't include the rear sway bushes so I used SuperPro bushes there.  At the same time, I replaced the shock absorbers with Koni yellow adjustables which were set to the OEM settings.  I retained the OEM springs.  I have not experienced any NVH and the ride, while firm, is much softer than the ride in my friends' vehicles which have been "upgraded".  Fulcrum Suspensions in Capalaba Qld fitted it all for me (with the exception of the rear sway bar bushes) and did an excellent job repainting all the suspension parts for me while they were out of the car.  I also replaced the ball joints, tie rods and the steering bushes at the same time.
 
When I drove the car away after all the work, I thought the ride was better and more comfortable.  This was possibly because the tired old suspension wasn't doing its job properly.  I agree with DTM that lubrication is very important.

Thanks for your feedback guys really appreciate it.
I've gone ahead and asked for a couple of quotes for Super Pro bushes so i'm just waiting for their responses.
 
Doc,
Its funny you say that because I'm actually planning to do the exact same thing expect i may add Eibach pro kit springs and i'll be doing all the work myself.

I also have the Konis with standard springs and Prothane bushings. Definitely not harsh. I was actually hoping that the difference with the bushes would be more noticeable as my car is not a daily drivers and is going to be used for track days. The fitting is very straightforward but I also agree that the lubrication is critical.
Peter

FYI the urethane bushes from TwosRUs and Prothane bushes I linked from Summit Racing are the same kit. Pricing is similar but you will find postage from Summit is much better than TwosRUs's standard international shipping of $50USD or more.

Thanks for the tip Maj, but i ended up getting a set Superpro bushings locally.
So far I'm quite pleased by them as they quite soft and bouncy compared to the Engergy Suspension set in my mx5.
 
Now i'll just have to set a date to install them.

So i've gotten round to installing my superpro bushes and i'd thought i'll come back to my thread to provide some feedback if anyone else was interested.
I've found the superpro bushes did not add any additional harshness or vibrations but you can definitely feel the car is taut when turning which provided a lot of feel to the car and over bumps they didnt feel any different over stock or my ae92 which was surprising. I'm very pleased with the results and if anyone is nervous about replacing their stock bushes dont be because there no negatives and there arent any other options available.
 
As a result of poly bushes It has also brought to my attention that the stock shocks and spring now make the car feel boaty so i'll be looking into a spring/shock combo in the near future.

Thanks koop; good to know.