HERES WHAT I DID ON MY STEALTHRAM TO CLEAN UP THE ENGINE AND MAKE MORE CLEARANCE FOR THE WATER NECK, (this is the heater manifold under/side of your throttle body for those of you that don,t know) this requires about 5 minutes work with the band saw and belt sander, and any machine shop can do it if you dont have the tools handy in 5 minutes if you show them the pictures, and YES IT REALLY HELPS CLEAN UP THE ENGINE COMPARTMENT AND GAINS LOTS OF WATER NECK CLEARANCE
and yes because it lowers the average incoming air temps the engine sees it allows a denser cooler air that allows slightly more fuel to be efficiently burnt to produce more hp, the amount is small but its there.(5-7 hp) according to what one of my friends saw after the change on his dyno run (NO I DON,T HAVE THE DYNO SHEET HANDY) AND YES ALOT DEPENDS ON THE OUTSIDE AIR TEMP COMPARED TO THE UNDER THE HOOD TEMPS INVOLVED, but I have no reason to doubt his word , and I find no down side after doing the mod to my vette, and yes it does seem to help slightly. and yes it will take your car about 2 more minutes to heat up at idle as far as the plenum temp sensor is concerned , but it runs great with zero problems, and yes your correct if you live where the temps get to below ZERO all the time it may not work for you!
ok first nothings free! youll need to use your skills.time and at least some money, Ill list what Ive found that works, first DO A GOOD TUNE UP!http://www.thirdgen.org/newdesign/tech/tpimod2.shtml
(1)the throttle body bye-pass above,(dont forget the heater manifold MOD ...AFTER YOUVE DRIVEN THE CAR FOR AWHILE to make sure it has NO BAD EFFECTS IN YOUR OPINION!) http://www.ws6.com/mod-8.htm
(2) air foils in the throttle bodybasically a waste of time and money but yes you can get 1-3 hp at 5000rpm http://www.ws6.com/mod-4.htm
(3) cut the top of the air filter cover to allow more airflow (worth up to 10 hp at high rpms) and install a K&N style high flow filter (this also helps but costs some money)
(4) remove screens in the M.A.F. this is good for about 100cfm of flow increase and is a good mod but can cause your engine to idle rough untill the ECU "RE-LEARNS" the differance in improved air flow)
(5) swap to synthetic oilan easy 3-5 hp due to reduced friction
(6) install an (X) pipe in the exhaustresults vary wildly but if you match this to a free flow exhaust and low restriction (CATS)or no-restriction (GUTTED CATS ) a 20-25hp gain is possiable at higher rpms
(7) kick up(ADVANCE your timing about 2 degrees) most cars respond well and it tends to allow the engine to rev, quicker
(8) porting your intake runners,plenum,basean easy 10-15 hp for a weekends work on the stock intake
(9) pocket port your cylinder heads/ reinstall with thinner head gasketa full weekends work and about $100 in gaskets but an easy 20 hp here if you know what your doing!
(10) install a better oil pan, by modifying the stock oil pan with an extendes sump and baffles lots of welding and measureong here but for several hours work and a scrap oil pan or scrap sheet metal,plus a few small hinges the stock pan can have the sunp extended forward and sideways enough that the 5 qt pan can handle 8 qts plus better control the oil (make all patterns from card board first and tape for welds untill you gett all measurements correct then cut the metal and weld the pan, make your mistakes in cardboard first
(11) 1.6 ratio roller rockers worth an easy 10-15 hp