We carry limiters from Rogue Engineering. They're made out of Derlin, which is much stronger than Poly or rubber. Having these installed along with Meyle HD RTABs is the best combination IMO. I have tried every single brand/Poly RTAB out there on my own E46 M3 cab and I prefer this set up. Another option is metal turner motorsport versions but require drilling of the bracket, where these literally slip in making installation a breeze even on your garage floor.
These require no maintenance unlike Poly bushings which will eventually crack apart, or require re greasing. ..not to mentioned increased NHV. Another fact is Poly isnt the best for all year use.
For the street, take my recomendation...I can guarentee you the majority of E46 M3 owners will agree.
. They definitely survived the test of rallying from here to Miami Keys and back, judgding from how many KM I put on my Conti Extreme Contacts vs my old tires...they seem to be keeping my toe angles in spec much better under load.
We have tons of these in stock, so let me know if you'd like a pair and I can ship it out to you if you like along with the RTABs themselves.