Going to be purchasing some uprated anti roll bar bushes and just been under the carea with a few open ended spanner's to check the size of my front and rear arb' and there both 20mm.... is this right?
I assumed the front was usually a bigger diameter than the rear?
Car is a blob 2003 WRX STi.

Thanks
John.

 

i believe front is 21mm and rear is 19mm, had the same dilemma figuring it out today! But the rear ARB had "19mm" on it

 

Yeah I had a feeling it was 21 front and 19 rear but I already ordered the bush's 20mm front and 20mm rear. Measured the front arb and it was 20mm the rear measured 20mm too but could if been because of rust build up etc. I too noticed the rear oem bush had 19 stamped on it.
It seemed to be a tight snug fit with 20mm on front and rear so I just left it as that. I'm guessing you have fitted your new bushes?

 

i too measured them and they seemed to both be 20mm, but i just went for what was stamped on the original bush, ordered 19mm for rear and left the front ones. Have you fitted yours yet?

 

Yeah I've fitted mine. I would personally go with 20mm on the front presuming your car is the same year as mine. But I could be wrong a 21mm may be the right size. But 20mm fitted pretty snug.