I have two Santy's with the 2.4L.  The 02 has the automatic and the 03 came with the 5 speed manual.  Although I must admit the auto is a bit sluggish at times, I would challenge any V6 Santy with an automatic to the first 500 feet of the 1/4 mile with the 03 and manual transmission.  I can easily spin the tires through first and second.  Third will just chirp if conditions are right.  The engine is completely stock, 88K miles.  The 02 with 123K and the auto benefits from the manual mode of the automatic transmission.  That way you don't have to wait for it to downshift before speeding up.

Supasing, try shifting the automatic manually if it has that manual mode to the right of the normal P R N D etc. This will allow you to maintain higher RPM's for a bit more acceleration.  It won't let you abuse it too much (I.e. it shifts on its own when you near the red line even though you selected a gear).  It will be slow off the line. 

More air is better.  Replace the stock air filter with a free flowing (non paper) one.  This is not as good as a cold air kit but at less than $50 it is a lot cheaper.  Make sure you use Iridium spark plugs as well.  Last, even though there are knock sensors that adjust timing when using lower octane gas, higher octane will perform better.  I know this from experience.  I travel a route that takes me over some low mountains regularly. With 86 octane and the cruise set to 65 two hills will cause a downshift.  With 91, and the same set speed, there are no downshifts.