typically, most aftermarket headers make about 5-7whp on a stock honda engine, including a B16. the SMSP headers are in a class by themselves because i think they are a little longer, taking up more room in the engine bay. i think with the SMSP you can expect maybe 7-10whp
most aftermarket air intakes make about 2-4whp, unless its a highly restrictive factory intake thats being replaced like the one on the RSX.
i wouldnt really expect more from the spoon parts. maybe an additional 1-3 whp over the norm at the most. as far as tuning with the ECU...now you're talking about significant gains. i think a realistic expectation would be about 5-10% more power by tuning with a programmable ECU on a dyno.