actually IMHO, if ur stock exhaust rear end pipe cannot be seen,
it might be better for u to have it sticking out.
reason is if it cannot be seen, most likely all that exhaust gas
will be beneath ur car, in the undercarriage. after some time, the
undercarriage will be full of exhaust gas and the car will have
difficulty letting off gas. by having ur pipe out in the open, its
liberating to the exhaust system. also, it could be a health hazard
to have all that exhaust gas under ur car.
just my 2 cents worth 
