if you plan on major mods please read this
I can't count the times I see this stuff on the boards and always wonder why people let themselves get into these situations.
If you're planning on modding your car past a cold air intake make your first mod some logging and tuning software or factor those costs in right from the beginning.
I see countless threads across the boards that go something similar to this " I have a bad idle with a heads/cam car and mail order tune". I'm not knocking the guys doing mail order tunes but getting an idle and basic driveability dead on through the mail is more luck than skill. Every car responds so different that it can only be "ballparked".
Also, have a goal in mind with your car and plan accordingly. Don't buy an hpp3 when you know you're gonna go heads/cam at some point. You'll be trying to sell the hpp3 because it won't be able to properly tune your car or you'll be running a bad tune for your setup. I'm not saying everyone should learn how to tune because for most/some people that's just not what they're into. At the very least you should have your own logging software and prior to doing major mods have a tuner picked out that's going to give you a good idle, part throttle, and dyno tune. Auto cars need to be tuned to the drivers needs. I've burned no less than 6-8 tunes on my car just for tranny adjustments. Granted, I've made changes to the tranny and rear along the way but it would've been tough to flash just 1 tune to cover the little stuff I wanted changed.
Some of the mail order guys will work with you on your tune and that's great but that's where the logging software comes in. It helps them immensely if you can log your car and send them the logs so they can see what the car is doing.
Logging software can also help you diagnose problems with your car. If you're planning on modding your car you WILL have problems along the way. It's just part of the game. Even stock cars benefit from having logging software.
Examples
My buddies c-5 was cutting out under full throttle. After logging I saw it was #7. Inspected #7 and found a small crack in the plug boot. Problem fixed.
Same c-5 was having different issues. Logged car and saw that an O2 was flatlining at 450mv. Replaced O2 and all was good.
Same c-5 this spring. Open loop idle was terrible then car would stall before going to closed loop. Really rich. Logged car and found a bad ect sensor. Replaced sensor and all was good.
Without being able to log that car it would've taken a lot longer to diagnose and fix those problems.
When doing mods don't forget about the pcm side of modding. Just a little free advice :D