you want more from your TPI ? well heres what works.
(1) get a low restriction air filter and install it
(2)pull that plenum off, remove the throttle body then inlarge and smooth the area behind the throttle body,siamese the openings in the plenums ports too the start of the torque tubes and open up and smooth the intake ports on the entrance of the torque tubes to match.
(3)remove the screens from the M.A.F sensor(be very careful not to hurt the filament)
(4)cut the heat sink fins inside the M.A.F. sensor too a much shorter length and smooth the ends to lessen the airflow restriction
(5)bypass the heater hose to the throttle body with a single piece of heater hose or splice the two ends with a short piece of pipe, that heat only hurts your performance once the engine is up to temp.(yes this part is a bad idea if its really cold were your at!)
(6)swap to 10/30 weight synthetic oil (if you have not allready because it has more heat protection and less friction than conventional oils)
the above changes will cost you (1) afternoons time , a set of intake gaskets and the use of a dremel/die grinder for a few hours, you will gain about 20 hp and cost very little!(yes it may idle a little ruffer untill it warms up but the difference will be something you can measure at the track. not some advertiseing jerks claim to sell something that is only marginally efffective at high rpm only!!