1.You can remove the MAF screen, some claim real gain, others scoff. 2. You can port and match your plenum and runners. I removed the humps in the plenum and the ridge on the intake side of the runners. If your Vette has allot of miles, there will be a considerable EGR buildup inside the runners as well. Cleaning them is labor intensive but just getting back to the original inside diameter will make a big flow difference. 3. Some claim rerouting the water away from the throttle body will increase horsepower. I bought a $3.00 brass fitting and a stainless line line for $12.00 to do this. You can use existing hardware and do this for nothing however. 4. The factory headers are very easy to remove and cleanup. The ERG lines protrude 3/8" to 1/2" inside the middle of the header outlet and the factory welds are very dirty and sloppy. Just removing the slag and reshaping the upper ports and collector side will make it flow much better. I have pictures of what I did if you would like to see it, just PM me. 5. Make sure your cat is in good shape, when I removed mine, there was a cup and 1/2 of debris inside. You have 2 options, one is to punch it out inside to improve flow, the other is to replace it with a high-flow converter. This will set you back $150 to $250 bucks. Don't forget to cleanup the flow on the cat as well. My guess is that if you put it on a dyno before and after, you will gain 10-20 RWHP. The biggest gains will come from the header cleanup, and the cat elimination. You can do all of this in ONE DAY easily, please let me know how much difference you feel.
Word of caution if you're grinding the header welds... you can easily grind all the way through them. I went ahead and welding a new bead on the outside. The last thing I wanted was them breaking away from the flange now that most of the weld was ground away.
1. Advancing the base timing to 8, 10, 12*. This will need to be done 2* at a time in the 1/4 mile. When the top speed drops off, back off to the last degree. Or use a scanner and watch the knock counts.
2. Set the minimal idle with the TPS voltage around .60v will add a little pep.
3. Cutback plugs. Cutting the tip of the electrode back some.
4. Clean the throttle body and IAC as regular maintence.
5. Place a nickle under the FPR diaphram will boost the fuel pressure.
If you remove the screens from the MAF, this usually ends up wil more trash on the hot wires (which the burnoff relay should take care of) and also make the air flow more turbulant. I've never heard of any gains from descreening the MAF or bypassing the TB coolant lines.
I would go after the factory headers if I were you. There is free horsepower just sitting there just waiting for you. Be careful not to grind too much but even if you did, it can be fixed easily. Just use good judgment. I was mad at myself for not doing mine along time ago. It's that easy to do and the factory ports are REALLY that sloppy. If you don't have a die grinder, buy 60 grit 1" flap wheels at the hardware store and put them in a drill. Use a file for shape and clean it up with the flap wheel. More airflow on the intake side without more exhaust flow will yield no results. The overall package and how the changes all work together is the prime directive. ALL changes have to complement one another. This applies to whatever mods you do.
upgrade on the earlier flat tappet L98 engines and its about as wild as the stock converter and rear gear will allow, YEAH it says the car needs 3.73:1 rear gears, THOSE GEARS will help, but it will WORK decently with the stock rear gearing
naturally adding decent flowing heads and a good intake will allow the cam you sellect to provide the power potential far above the stock combo, but if you get more durration than the listed crane grind your very likely to need more compression,a 3.73:1 rear gear, and with an auto trans a higher stall converter