possible bent frame on buddys 95 5.0

[Rollinastang]

hey my buddy has a 95 5.0 convertable. he just added and exhaust to it. when he jacked it up he jacked up the rear and put it on wheel ramps he then jacked up each side of the front (right then left not both sides at the same time) and put stands under it. exhaust sounds great but he notices the car pulls slightly to the left now and he just had his tires rotated but he thinks jacking it up this way being a convertible may have bent the frame some he is not sure. is it possible it bent this easy? and if it is, is there a way to find out if it is bent without taking it to the shop?...also i did mine the same way and mine doesen't pull. i have an 03 v6 is it possible i may have damaged mine too but not so much that it is not noticeable yet? Thanks all my friend will appreciate your input.