Phantom - you can make a car sound any way you like via the correct selection of exhaust components etc. As for cheap mods ... let me ask you a couple of questions and give you a couple of suggestions. More suggestions await once you answer my questions
Q1: Is this a V8 or a V6?
Q2: Is this an early model series 1 or a series 2?
Q3: Auto or Manual
Q4: IRS?.... LSD????
The above can also alter the recommendations below. For this part I will assume you have an Auto V6 as they are more common. I too have this vehicle and can hopefully assist you.
1. Your pod filter, make sure its gonna breath well with by both a ducting air from inside the wheel guard and/or front bumper, and by making sure you have a heat shield between the side of the pod and the radiator. Not that a pod will give you huge gains, but if its sucking in hot air you're not going to notice its benefits at all. I myself run a stainless intake pipe, a SplitFire pod, aluminium heat shield (basically an bent offcut bolted onto the three pegs the factory airbox used).
2. Bellmouth - a lot of different stories on this one, good and bad... on the bad side, you're idle may become rough, but it will work together with (1.) above and the next (3.) item to allow more air through.... air = power. There is a diagram under the Howtos in "General" discussion on this forum, and I am sure there is a guide to help you in there as well. I removed mine in about 20 minutes, I was performing item (3.) at the same time, so too easy.
3. Oversized throttle body. A pod is all well and good, but if you're unable to use that extra air, there is no point. You can get adaptor plates for things like FITs oversized TBs, you can get exchange ones, or you can get yours custom bored. As finding a V8 one was impossible for me here in Perth, I got mine custom bored to 65.1mm for $250.00 (about $100.00 less than most exchange ones, and without the hassle of fitting a non standard unit). This allows me to use 15% more air, all good.
NOTE: the above mods will certainly increase your airflow by 15% or more, on the down side... more air although giving more power.... needs fuel to do that. Economy rate will suffer.
4. Get a nice set of headers and an exhaust system. I myself have not yet fitted an exhaust (as I am considering a turbo kit which may make me buying the headers redundant) and am looking at a nice set of Pacemaker headers, a 2.5" mandrel bent pipe with high-flow and tubo Lukey bits. This will make the car a little bit louder than stock... and when you stomp it a fair bit louder... but generally offers you a nice increase in power, while remaining fairly quiet as you require.
5. Auto trans upgrade kit. Not sure if they are around still, but places like C.A.P.A offered a new PCB for Holden GM 4L60-E 4HDD Autos, apparently working in tandom with the ECU to give you better shifts etc. Alternatively you can consider a gearbox conversion to a manual. Plently of people are doing adaptor plates now for Supra boxes, as well as actual VR manual boxes. This is not cheap though (think about $3000.00 or more) for the conversion - but this will get you a nice new clutch, pedal box, wiring harness, manual ECU, and all the fruit. I have just had mine converted and the LOSS that the auto had was remarkable. Heaps more power actually getting to the rear wheels now after putting the manual in. I would say the CAPA kit would work the same way for you.
6. Differential - a VR, or at least most, will have a live/beam axle open centre 3.08:1 diff - this, while good for "cruising", economy, and top speed, is terrible for performance. You may wish to speak to gearbox centres near you to suss out an LSD and/or higher ratio conversion. I am getting a custom 3.45:1 LSD made up and fitted to mine, using a 3.45:1 centre from a wrecked VL Turbo. 3.45:1 will give you much better accelleration, while remaining reasonable in the economy and drivability stakes. Another option is the 3.71:1 but thats just stupidly quick.
7. Flywheel - when getting the gearbox mods done (if you go down that path) why not get a FIT or CarToys (I think) flywheel... or get your own shaved and balanced. While this won't make a lick of difference to your dyno score - it will help build up revs quicker - in combination with the shifter and the diff means way quicker off the line.
8. Computer - The ECU stuff can be quite expensive, but all thats required is a few hours labour, a blank, your existing ECU, and a few dyno runs (or road runs if your on a tight budget)... oh... and the Kalmaker software worth like $3,500.00
... if you can get a deal on tis, way recommended. IN FACT - if you have a manual (or get a manual conversion done) the program is a lot smaller, and you can actually (apparently) use a toggle switch and run two different performance programs. Please note however that the GM ECU program does actually rock - and unless you do some mahor tweaking won't actually give you too much performance.
---
Thats all I can really offer at the moment. Other things like forced induction, heads, rockers, cams, pistons, fuel systems, etc etc are definately not a "budget" item.
Hope it helps. SOrry for the long post.
