Investment in Mods - Part Three

In the previous two parts of this series we’ve focussed on presentation – interior and exterior enhancement. In this instalment, the final, we’ll examine ways to get your car running harder without causing potential buyers to run.

Performance Mods

Exhaust

An upgrade exhaust should be one of the first power-up mods on your list – and you can choose to go ‘mild’ or ‘wild’.

Wild exhaust systems (ones with polished canon mufflers set at an angle, huge pipe diameter and minimal noise suppression) may suit certain buyers of a select category of vehicle but a wider buyer group will appreciate an upgrade exhaust that’s less overt.

Let’s say you’ve got a LS1-powered Holden and you want a nice V8 burble with a bit of extra grunt. Our first suggestion is to replace the factory muffler(s) with generic straight-through mufflers made from mild steel – nothing too flashy. Whack on a chrome tip or two and you’ve got a presentable upgrade from as little as about AUD$100. And it’s an upgrade that few people will dislike.

But what if your focus is maximum performance?

In this case, we recommend fitting an upgrade system from the extractor flanges (or off the back of the turbo in the case of a turbocharged car). Good second-hand systems can be found for popular high-performance cars but usually you’ll need to go for a custom exhaust fabrication, which costs anywhere between AUD$300 to well over AUD$1000.

The headers of a naturally aspirated vehicle are also commonly replaced fairly early in the piece. Aftermarket extractors cost a few hundred dollars but, again, consider bolt-on OE upgrades – for example, the Holden VZ-type LS1 headers are a bolt-on upgrade for all early LS1s.

If all this sounds a bit too expensive, you should consider a cat-back exhaust. A cat-back exhaust begins after the factory cat converter and is a good intermediate upgrade. Note that on some vehicles you might be able to enhance the exhaust with second-hand OE parts – for example, a HSV system bolts on to Holden V8s and Impreza STi systems bolt on to WRXs.

Air Intake

Just like the exhaust, the air intake can be modified with a wild or mild approach.

The most extreme intake mod is to rip out the factory system and whack in an aftermarket pod filter. A flashy one with a powder coated mounting brackets and all the gloss typically cost around AUD$200. Pod filters generally provide a massive increase in intake airflow, but all too often they are installed so that they suck hot under-bonnet air. This is a negative for any go-fast enthusiast with their eyes open and furthermore it’s a dead-set put-off for buyers wanting a stock looking car.

So there you are - you’ve spent a couple of hundred on an aftermarket filter kit and it doesn’t appeal to anyone. Not what you want.

A better approach is stealth modification to the factory air intake. Remove the existing snorkel that feeds air into the airbox, enlarge the opening into the box and make a custom snorkel from PVC pipe. PVC pipe can be easily worked into shape using a heat gun to soften it and, once set to the correct shape, you can finish it off with a can of black paint. This mod can easily go unnoticed by many buyers. Those that do notice generally won’t have anything to complain about anyway. This is an effective and safe mod – so long as you position the air pick-up somewhere it won’t ingest water, rocks, bugs, etc.

Boost Controllers

There’s a multitude of ways to increase boost pressure on a turbo car but unfortunately there’s a large number of people that persist using home-grown systems that give poor control.

A home-made boost control system can perform well BUT ONLY IF THE SYSTEM HAS BEEN PROPELY INSTALLED AND TESTED. And that means fitting a boost gauge, monitoring boost pressure over a variety of driving conditions and temperatures and – probably – making some small tuning changes.

If you can’t be bothered tuning your boost control system and integrating it under the bonnet, we suggest that you remove the system when it comes time to sell; nothing repels buyers like a dodgy-looking boost control system.

More elegant Do-It-Yourself approaches include fitting a variable restriction in the hose to the boost control solenoid (see Bumped Up Boost) and using the newly released Digital Pulse Adjuster from Silicon Chip magazine, that can be used to control the factory boost control solenoid. Note that these approaches are suitable only for cars with factory electronic boost control.

But it still seems that buyers like to see a recognised brand name when it comes to boost control. HKS, A’PEXi, TurboSmart (and others) sell a variety of pneumatic and electronic control systems to suit a variety of budgets. They generally cost more than a home-grown system but they might pay off in the long run.

Engine Management

When you want to modify the air-fuel ratio and ignition timing of your vehicle there are a few approaches. But which one makes the most economic sense?

Well, interceptors are currently popular because of their universal application, relatively modest cost and their resale value – people invariably remove interceptors from their vehicle and sell them separately. The resale value of a second-hand interceptor is very good, which means you might lose only a couple of hundred bucks in the scheme of things.

Another relatively low cost approach is a custom chip program. Note, however, these can be performed on only certain vehicles and many can’t be programmed in real-time. The advantage of a custom chip is seamless integration and the flexibility to access a broad selection of parameters (such as rev limit). The downside is limited resale-ability – you can’t sell a custom remap and it might be a put-off for buyers wanting a stock car.

Clutch

If you give your modified streeter a workout on a regular basis, chances are the factory clutch will start slipping. So what should you replace it with?

Well, pretty much anything except for a button clutch; these are completely unsuited for street use and generally have poor service life. Instead, spend your money on a high clamping force pressure plate (perhaps a modified version of the factory part) and talk with your local clutch specialist on the suitable clutch lining for your application.

With a beefed up pressure plate, the vehicle’s clutch pedal will be heavier but the engagement is a lot smoother and more user-friendly than any button clutch. There’s also hardly any difference in cost – so the choice is clear.

Return the Car to Stock? We’ve touched on the idea of removing modifications when it comes time to sell – and the concept deserves some discussion. In many instances you’ll recoup more money by removing your aftermarket wheels, audio system, exhaust and interceptor and selling them separately from the car. There’s plenty of demand for this sort of equipment on the web, local classifieds and through car clubs. As a guide you can except to recover about 50 percent of your initial purchase price - and you can sell the car as a stocker. As mentioned, a stock car appeals to a much broader range of people than a vehicle with your personal selection of mods. But there are some exceptions. In the case of popular performance cars, some buyers prefer to buy an example with all the bolt-ons already included – they know it’ll cost more to go out and purchase the parts separately and fit them to a stocker. As you can see, there’s no clear-cut direction to take – in some instances it’s beneficial to remove your mods and in other instances it might not be. When you decide to sell your vehicle, we suggest that you compare the second-hand price of stock and modified examples of your car and make a decision based on the price difference.