Coupe 2.5s w/ Cat-Delete, Exhaust problems

[ReviT]

Ok so i have the stillen axle-back on my 2.5 coupe. Now when i first put the mufflers on everything sounded good there was no rattling or anything but i still had the really restrictive stock exhuast system. So the first step i did was take it to a muffler shop and had them run a custom 2.5 inch pipe from my cat up to the stillen y pipe. Now i started to notice a little bit of a rattling from the exhuast when it was still cold. When it warmed up it owuld go away. Now i just ran a cat delete on my car and first off you will not believe how restrictive that cat is. Worst design i have ever seen period. Well with the cat delete i opened up alot better flow in my car and my cat is no longer absorbing large amounts of heat. Well the problem i have is now the rattle is 100times worse than it was before and doesnt go away at all. It stays with the car and comes out of both the mufflers. Anyone know what would cause this? Cause hte rattling did start when i first got the cat piping done. 2 friends of mine used the same shop and have some rattling also. If you guys have any questions or anything about what i can do please let me know as its driving me up the wall. ITs incredibly loud rattling and instead of the deep throatty that you hear when the car isnt rattling all you hear is a high pinged garbage sound.

[jungleboogie]

hmm... maybe piping vibrating due to contact with lower strut brace? i've never seen the undercarriage of an altima yet, but i had a similar issue with a custom exhaust on my older civic... if we're talking about the same thing, then i know it gets quite unbearable.

[ReviT]

hmm... maybe piping vibrating due to contact with lower strut brace? i've never seen the undercarriage of an altima yet, but i had a similar issue with a custom exhaust on my older civic... if we're talking about the same thing, then i know it gets quite unbearable.

I thought about it rattiling on something but its not. Me and my mechanic both looked under the car on a lift and saw that it wasnt hitting anything... The sound is coming directly from the mufflers as well.