Some Questions About Custom Tunes

[Exile]

I recently picked up a 95' GT 5.0 with the following...

Rebuild 306 ci
Forged Speed Pro pistons
Stock intake & throttle body
Ported heads with Crane 1.7 roller rockers
B303 cam
30 lb injectors with matching MAF
BBK cold air intake
BBK headers, H-pipe, & Flows
Mallory Distributor
Custom tune/chip (code 511)

I am wanting to put on a Cobra intake with a 65mm throttle body, and possibly step down to 24 lb injectors. Then maybe later on putting on some GT40 heads.

Will making these changes throw off the custom tune/chip to where it wont run/drive right? Or will I HAVE to have it re-tuned afterwards to make it run right? Or will I be ok with these changes and keeping the same custom tune for right now?

Will playing around with and re-setting the distributor/timing have any effect on the custom tune?

Im just not too familiar with whats all involved with custom tunes, and I just don't want to start messing around with it and changing things right now if its gonna mess anything up to where I will have to go get it re-tuned to run/drive right?

 

[Decipha]

I just replied to this same question earlier on corral

slap the cobra intake on her with the t/b, that in itself won't require any tune changes

24s will require tune adjustments, its useless to go with 24s keep what you have, the 30s are much better injectors than 24s and safer too

adjusting the distributor will only slow the car down if its tuned correctly, if its not at 10 dbtdc it will throw off the ecu's calculations

here's all the info you need to know
http://info.efidynotuning.com/post.htm

just scroll down to the bottom where it lists when retuning is required

 

[90lxwhite]

I just replied to this same question earlier on corral

slap the cobra intake on her with the t/b, that in itself won't require any tune changes

24s will require tune adjustments, its useless to go with 24s keep what you have, the 30s are much better injectors than 24s and safer too

adjusting the distributor will only slow the car down if its tuned correctly, if its not at 10 dbtdc it will throw off the ecu's calculations

here's all the info you need to know
http://info.efidynotuning.com/post.htm

just scroll down to the bottom where it lists when retuning is required

Yeah what he said. The only thing that will affect the tune causing drivability issues would be changing the maf and injectors. I'd keep the injectors you have and really I probably wouldn't spend the money on an aftermarket throttlebody if you're staying fairly conservative in the power department, ie Gt40 heads. The reason you read about the fox guys upgrading to larger tb's and maf's is theirs are only 58mm where as the 94/95's have 60mm tb's and 70mm maf's.The 94 and 95 Cobras and GT's had the same size maf's and tb's. Bolt on parts such as maf's and tb's don't actually make power, they "support" it. When the heads start pumping more air than the fore mentioned parts can handle it's time for a larger size. My 95 GT makes 332 rear horsepower with the stock tb and maf. A gt40 head and intake motor won't make quite as much (rough guess 270-280 rear horse on the high end) and switching to a larger throttle body will yield very little to no gain. As for playing with the timing, leave it alone. When a car is tuned the base timing is set at 10* and the timing advance is written in the tune and controlled by the computer. Final timing is set at the optimal degree that the car can handle w out detonation and driveability issues. My base is set at 10* and final is 22*. So if it has been tuned it is already where it needs to be. Was the car dyno tuned w an sct chip or is it a mail order tune such as Bama?
To sum it up: What I would do is add the explorer/cobra intake (don't forget the elbow adapter if the intake came off of an explorer), keep the stock throttle body (save that money for heads and intake), leave the maf and injectors alone, and after you install the gt40 heads go get a re-tune for optimal power.
Ps: Mail order tunes are just a guessing game and dyno tunes see what's going on in real time and add or take away fuel as necessary to make the most power out of your combination. Also the maf can be "calibrated" to match any injector size via tune. Don't buy a new maf.