GT4 Exhaust Help Needed, Cant fit it Options

[3SGTE]

Bought a stainless steel cat back exhaust for the gt4, a mongoose to be exact. i took it to my local exhaust garage, a well known garage, and they told me to fit the exhaust you need to drop/lower the rear subframe and possibly the front just to get the exhaust fitted.
Is this true?? plus the stock exhaust is ovaled at the front subframe to fit snug, and the new s/s exhaust system isnt, will this make a difference?
Thanks guys!!

[DEATH]

they told me to fit the exhaust you need to drop/lower the rear subframe

That's highly possible if there is no set of flanges above the rear axles [like USDM stock has over the rear suspension]. As for the rest - I could see that being the case if the entire exhaust is one peice [you'd know cause the box it came in would be as long as your car] or if they did a really terrible job of breaking it down into sections. Overall, I'd say this is highly unlikely if the brand is at all reputable [never heard of a mongoose exhaust before?].
Even if that is the case, have this "well known" shop cut the exhaust into 3 peices and weld flanges to join it back into one peice. Seems like that should have been their first thought after "WTF?!?"