Is it safe to drive my truck to the muffler shop (about 3 miles) with just the downpipe. I didn't know if the lack of back pressure could do any damage to turbos or motor.

 

Isn't that the whole idea of 4 and 5 inch exhaust, to eliminate backpreasure? I don't see a problem with it.

 

I wouldnt worry about it, just make sure its clear of wires/lines directly in front of the opening as the exhaust will still be pretty hot at that point.

 

Don't get on it.

 

I drove mine for 3 or 4 weeks with just a D/P , my exhaust rusted/broke off , and my 5" was in shipping , I had the downpipe ,and the intermediate pipe that used to go almost to the cat. Aside from turning my rear axle , spare tire , bumper , and tailgate black, I never had any trouble.