Ok im running flowtech shorty headers with y pipe to no cat, bolted flange to borla catback i notice the whole exhaust moves while the motor is running there is no flex pipe installed i was wondering if installed one where the cat was will this help with taking stress off the exhaust system ????

 

Yes it can take the stress off. Alot of cars come like that from the factory. My gmc truck has one at the y pipe. I ran two in my dual exhaust