Theres a few more simple mods I'd like to do to my car within the next year and a half. I don't really want to go with a bigger engine since I'd like numbers matching with my Heritage, but I wouldn't mine some more show and some more go under the hood w/ that old 305. Anyway, heres the ultimate plan:
-Hooker 2055's with some kind of coating, probably jet-hot
-Ported and Polished Plenum and Runners
-Air Foil and new air filters (K&N's unless another brand is better)
-Chrome/Polished Underdrive Pulleys

First off, I know the air foil is highly debated but I figure it can't hurt. Second, I also know that underdrive pulleys have mixed responses, but if i'm gonna bling out the rest of the engine bay, why not make the front of it look nice too.

As far as the porting...would it benefit me? All the topics i found while searching were related to L98's...so I dont even know if porting my plenum/runners would give me any gains. Some things I have found say that the TPI intake is fine in stock form for a 305 since it helps with the torque of the engine.

Any input regarding these potential mods would be greatly appreciated!

 

i would first do the whole exhaust, then gears. save youre time and money and forget the plenum, unless youre doing a cam or a power adder. airfoil $50 so why not?

 

CAI, headers and a set of 3.42s gears will make a noticeable difference. My 91 GTA felt like a dog off the line when I had 2.73s but now I have 3.42s and I can roast the tires. You may have to put up with a bit of gear whine though.

 

If you think 3.42s are bad, try 3.73s!!! I just switched to a 3.42, but when the old rear was in, it really jumped! People thought I had a 350.

 

I wouldn't bother changing the intake on a 305 TPI, it gets enough air already.

The 3.42's are a very good idea, 3.73's on an auto trans are maybe more than I would go with.

If you're not going to do head work, or a cam, I'd consider installing 1.6 rockers, and new valve springs as well.

 

What is the best brand of gears? All i see in summit are motive and richmond, but i've heard people talking about GM gears.... Also, can i get a set of 3.42's that work with my posi carrier? Oh, and what is the typical RPM cruising speed at like 70mph w/ 3.42s?

 

Here is a link for the package I got for my 91 GTA. I got Strange 3.42s (2-series carrier) and Royal Purple diff fluid. You need gears for a 2 series carrier so that your posi will work. At 74 mph, the rpms will be at around 2300. You also need to swap your drive and driven gear so that your speedo is accurate.

http://www.thunderracing.com/catalog...&vid=6&pcid=68

 

Have you changed the coil yet? The stock GM coils are garbage. Change to an aftermarked direct replacement coil. I like MSD, but I'm sure Accel is fine too....you'll get better mileage as well. Oh, change the plug wires too.