^threadjack = bad D
and +1 on what Ed said -
make sure your stock system is functioning correctly before trying to mod it
first "mod" on any TD is : open up the exhaust system !
factory pipes are small and poorly bent,
and muffler & cat are restrictive relative to newer 'hi-flow' units (or none at all

)
normal muffler shops us a bending machine which produces "crimp" bends;
the bends will be ridged & neck down the ID of the pipe,
both of which hurt flow
our vendors sell "mandrel" bend 2.5" and 3" pre-bent pipe to fit our TDs;
the bends are neither ridged nor necked down = Great flow
price (with shipping) is often close to what a muffler shop will charge;
of course then you have to install it
but AT MINIMUM get a local exhaust shop to bend you a 'cat-back' with 2.5" and ditch the muffler (should cost $100-150);
that will really wake up the engine ..
(probably not legal where you're at to eliminate the cat... if it was, I would,
but then you prolly need to add a muffler for noise control, or replace OE cat with a 'hi-flow' cat)
oh yeah install a boost gauge too