After squeaking problems on 147 (diagnosed to be anti-roll bar) after only 15-16.000 km (see this threads: http://www.alfaowner.com/Forum/showthread.php?t=30927 (Squeaking 147, polyurethane bushes, 147 aftermarket anti-roll bars...) http://www.alfaowner.com/Forum/showthread.php?t=15132 (Lowering 147: experiences??)
http://www.alfaowner.com/Forum/showthread.php?t=21993 (squeaking front suspension wishbones)
), I have decided to put bigger anti-roll bar and Bilstein Sport front dampers, since all front suspension is going to be dismantled anyway. Decision for installing Bilstein is made because of definitely too soft front suspension (also on this forum there was a lots of discussion about this - and lots of reviews on various combinations), very bumpy ride on bad roads, with possible bottoming out on big bumps and police slowing bumps, to minimize roll while driving on curvy roads, and because I DON'T want to lower car.
First, info about anti-roll bar: 147 GTA anti roll bar CAN be fitted on normal 147 (there was discussion about this: http://www.alfaowner.com/Forum/showthread.php?t=31350 (AutoDelta Anti-Roll Bar Kit on 147 1.6 TS)
http://www.alfaowner.com/Forum/showthread.php?t=30927 (Squeaking 147, polyurethane bushes, 147 aftermarket anti-roll bars...)
) without any problems. They even have same diameter, but 147 GTA anti roll bar is heavier (read somewhere that normal 147 anti-roll bar is hollow, and 147 GTA is not). I was looking also to put Eibach (Autodelta or similar) anti roll bar but it is way too much expensive (pair more than 550 EU, pair front-rear of original 147 GTA 240 EU) and they come unprepaired - have to dismantle old bar and take mountings for bushes and fix them to Eibach bar.
Work involved to change anti-roll bar is colossal!! They dismantled half of the car to change it
Review: improvement is big, less roll in curves, less diving during heavy braking, and surprisingly more comfortable driving on bad roads which I am not surprised because of other reviews on this forum (original dampers are definitely badly designed and low quality stuff).
So as a conclusion I must say "must have" especially if you don't want lower car.
Soon I will install also rear 147 GTA anti-roll bar (unfortunately did not arrived in time to be installed with other parts), but it is easy job, I will do it myself.
Few more info: spraying of suspension bushes with WD-40 or special oil does not work on anti-roll bar and upper wishbones on permanent basis. On upper wishbones oil can't get inside, while antiroll bar bushes are impossible to reach from inside side.
Just to prevent future squeaking on upper wishbones, they dismantled them and put special grease inside (typical cure for squeaking upper wishbones, if rubber is not ruined yet)
Also I was surprised to see that bushes of anti-roll bar are special ones with textile-teflon from inside where bar is rotating and they tend to squeak after only 15.000 anyway???
PS installed also oil-temp gauge, but I will make report with know-how instructions in few days after taking some pictures.