I ask many question because I want to understand how work the pcm and the rest of the car ,I try to make my car faster with the experience of the others peoples try on there car(it' difficult in english)I think that before spend much money on a car,many fine tuning can be make.And everywhere or often many talk about this product or another products,but we never had a race result before and after on a race track.I see often contradiction on the forum...like thermostat.....like ait sensor....I just want to be certain before make a 500$ move.Before my SSEI I had a chevy montecarlo 1979 with only a 267,after 10 years ,the glory was not to run 13 sec. on 1/4,but to run hight 15.I remember a man that I followed his trans-am gta on a 1/8 track,he come to see me after the race because i lost the race ,but the man and his friend thougt that i had a 350,it'* the glory for me .....I' m surprise when I see on the forum peoples spend sometime 350$ for 10 hp......I know that take a car from 16 sec. to a 15 sec. is easy but to pass from 15 to 14 is more difficult...I just want to see the ratio between money and gain,I started to race in 1987...And I saw many peoples buy headers 500$ for a 3600pounds car with 2.29 gear.......sorry for my english......and sorry again for too much questions....thank you again

Franois, the little tuning items I see you post about are items you need to deal with AFTER adding more power in a conventional manner, but only if you need to.

Your car will run better with the fewer little tweaks you have to do. There is no contradiction on this Forum that I'm aware of regarding the IAT or Thermostat. 180 thermostats are for 99% of the cars here. 160'* are for the track queens that are heavily modified, and tweaked to work with it. IAT contradiction may be a misunderstanding on your part. There is a difference in how that sensors input is used between OBD1 and OBD2.

In OBD2, there is a MAP sensor as well as an IAT that are used to calculate timing advance. This is why on a stock OBD2 PCM, the IAT trick won't benefit you.

In OBD1 (like yours), the MAP sensor is ONLY for your boost gauge and isn't a calculated part of the timing equation. You CAN trick your timing to advance in this manner, but you will be asking for trouble with your current setup. Your car at this point isn't ready for more timing without great risk.

If you have about 500 to spend, I'd concentrate on the basics for now. Get a better intake (FWI), keep the 2.5" pulley for now, and remove your exhaust manifolds. Repair all the cracks (remove all the heatshields), and stitch-weld the outside of each runner to the flanges, then port out the OEM welds. Between the intake and exhaust manfolds, you'll gain 15-25hp and it will set you up nicely for more power. It might also be a good time to port-match your LIM to your cylinder head ports (PORT-match, not Gasket-match).

Many of the little 'tuning items' are just that. For tuning. Not for power. If you want to make real power, you have to flow better all through the engine.

In the meantime, start saving up for a transmission. You'll need about 3-4 thousand for it before long. As soon as you start modding a car of that age, it'll be coming. And you can regain much lost performance with a good rebuild, and even more with a good shift kit.