Sorry to hear youre having problems with your car and the dealer but me too i've been having vibration problems even when i had the stock wheels on and if i can remember clearly it was around that speed as well (mine is RWD by the way) and also this is sources chrysler??, im surprised cause i used to go to pie-ix but they screwed me over with warranty issues and tried to make me pay for my alignment!, i was furious!!!

,so after that i've been going to sources ever since and they take care of me very well, and i know the president there,one of the service managers, very nice guys ,much better than the a-holes at pie-ix ,thats for sure! Well anyways i hope everything goes well and you solve this problem and by the way,im pretty sure ive seen your car there, its very possible that it was yours considering the fact you brought it there like 7 times already.
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2005 300C MIDNIGHT BLUE
tints 35%front 5%rear
stage 1 jet chip
t-rex hybrid series triple chrome plated bentley grille
eibach sportlines
spare tire removal : (+20rwhp)
22" wheels
pirelli tires
22" & DUB badging
SRT-8 trunk lip spoiler
volant CAI
dynatech headers
borla cat-back exhaust
VIP bodykit, headlight covers and roof spoiler
hid fogs
ultimate pedals
imitation side ports/vents
stealth package
lambo doors