need to build my intercooler piping. i bought a basic set of aluminum bends off of ebay of unknown material grade. i am building 2.5" from the turbo to the intercooler, and 3" from the intercooler to the throttle body, however the inlet and outlet of the intercooler is 2.5", so i was going to weld a 6061-t6 transition in the piping to go from 2.5"-3"...Should i have any concern welding this up since i don't know exactly what kind of aluminum it is?

also, what is the typical rule of thumb when welding diff. aluminum materials together?

 

4043 filler is a good all around filler for aluminum it will work fine for what your doing.