I have a 92 RS 5.0 TBI with 100,000 miles
I just recently had the automatic transmission rebuilt with a shift kit, got a cat back exhaust system, and have replaced spark plugs, wires, distributor cap, and rotor.
It has 2.73 gears obviously.
The car doesn't feel like its living up to its potential
Should I replace the cat?

What should be my next step in improving performance. Prom Chip? Air Intake? Headers? Throttle body mods? I really don't want to do any real engine mods like cam or heads at the moment. How could I get the car to perform at least 15.0 sec. quarter mile runs? I would like some opinions on the most horsepower for the money.
I was thinking about Air Intake because it pretty much looks like the engine is breathing through a soda straw, I mean would you breath well through one? But then again the only aftermarket air intake is made by slp that I know of and I've heard some rumors of the single inlet being on the passenger side of the car instead of the driver side.

 

The best thing you can do for a 305 (cheaply) is to help it breath right. Do all of the Ultimate TBI mods in the tech section. Most of those are DIY and above all FREE!!! I just recently put an open element air cleaning assembly on mine and the seat of the pants difference is noticable! (The change in exhaust sound isn't bad either) Go with a K&N or Holley Power Shot filter element. Coupled with headers and a Prom, the Ultimate TBI mods will get you a long way and cheaply! A free flow cat will help too, esp. if yours is OEM.

 

When I still had the L03 in my car the best mods that I did I think were:

1. headers
2. gears
3. UTBI Mods/Open Element

If you do/can do head work getting a pair of old, cheap 305 TPI heads are well worth it. The swril port heads on that motor are nasty and just about anything is a upgrade. The L98 Alu heads are sweet but can be kinda spendy + you need to get them milled.

 

definetly do the ultimate TBI mods and the open element...i you dont have to mess with the intake right now because it wont help much since you have the crappy heads and the cam in there...but iyt may help alittle...defiently get a new set of gears...you can probably find a posi rear from a TA with 3.42 or myabe 3.73 grears for cheap

 

when you guys mention the ultimate TBI mods, what are you refering to???

 

The Ultimate TBI mods can be found under the Technical Articles in the Carb/FI section. They were authored by Pablo Morales (olbap@bellsouth.net) and include a lot of "free" mods that you can do to your tbi to make it flow better. Including: air cleaner/induction, throttle body "port and polish", injector spacer, etc.