DIFFICULTY LEVEL: 1 out of 5 EASY!
MATERIALS REQUIRED: Domin8r Exhaust system, penetrating spray, anti-seize paste
TIME: 2 hours
Want to unleash more power, torque without it affecting your fuel economy? By fitting a high-flow Domin8r exhaust system you can have your cake and eat it too!
A quality exhaust system not only makes your 4WD sound better, but it also lets it breathe better, improving acceleration, power and torque right across the rev range. It’s made possible by removing the restrictive factory exhaust and replacing it with a high-flow system specifically designed to make power where we 4WDers need it. Thing is though, not all exhausts kits are created equally and you really need to know what you’re looking for to avoid paying too much.
Firstly, to get real results you’ll need to replace the whole system from the turbo back, not just from the catalytic converter back. Look for a kit that includes a high-flow dump pipe, catalytic converter and muffler, one that is already fitted with EGT and air/fuel sensor ports, has interlocking flanges and is constructed out of either 3in mandrel bent aluminised steel or 409 stainless — anything less just won’t cut it in the bush.
One system that delivers just that is the new Domin8r exhaust systems. Supplied as a full DIY bolt-in kit and posted to your door, all Domin8r exhaust systems are designed to be fitted at home without any need for cutting, bending or welding; and with kits starting from around $650, the Domin8r 3in high-flow exhaust system represents great value for money.
Let’s take a look at just how easy it is…
If your 4WD has seen its fair share of mud, dirt and sand; there’s a good chance the bolts and flanges will be covered in dirt, grit and corrosion. So first things first, it’s best to start with some penetrating spray like Inox or WD-40 onto the dump pipe nuts, flange bolts, rubber hangers and mounting bolts, to help make removal easier. If the old hangers have started to perish, grab a new set before you hook into the job, so you’re not stuck with the truck pulled apart in the driveway while you solve the problem
Now that you’ve given the penetrating spray some time to work, get onto the bolts that are holding the old system in place. The first flange to undo will be located just above the rear diff, and is held together with two 14mm flange bolts. Undo them, then pry the rubber hangers off the mounts using some spray lube to help ease them off. If you don’t have a can of spray lube handy, try using soapy water to help slide the hangers off with a pry bar. This should see the rear muffler and section come off
To avoid rounding off any nuts or bolts, use single hex sockets and spanners for the job at hand. There are small differences between metric and imperial sizes, and if you get it wrong, you could end up turning a 2 minute job into a 2 hour headache. Generally, Japanese Nissans and Toyotas use metric fasteners, while American and European trucks use imperial. Exhaust fasteners aren’t very forgiving, so taking it easy is the trick to avoiding trouble along the way.
Next you’ll get stuck into the centre muffler or the centre section. The same applies to this section with bolts and hangers, removing the whole section and getting it out of the way. To avoid overloading the dump pipe and flex joint once the rear hanger is removed, you may need to support the weight of the exhaust with a jack or stand
With the centre muffler removed, all that remains is the catalytic converter, flex pipe and dump pipe. In our case, our D-4D HiLux utilises sprung bolts and a dome-shaped gasket in place of a traditional flexible pipe, which is easily removed. Just undo the two 14mm bolts holding the catalytic converter flange in place, pop the hangers off, disconnect the O2 sensor and then remove the pipe
The final piece of the puzzle is removing the dump pipe. First, you’ll need to remove the turbo heat shield in order to gain access to the top dump pipe nut — it’s a pretty simple job as they’re generally only held in with a few 10mm hex bolts.
Most of the time, the dump pipe will only have a handful (3 in our case) of locking nuts holding it up to the back of the turbo. The bottom nuts can be tricky to get to, but can be undone easily with a socket, a few extensions and a swivel joint. These nuts are often quite soft, so take extra care not to round them off
With the old dump pipe removed, now it’s time to prep the new exhaust for installation. The Domin8r system we’re installing has a pre-fabricated threaded port for an EGT sensor, and a second port for an air/fuel ratio sensor. The HiLux we’re installing it into doesn’t have any gauges installed, so we simply tightened the supplied bungs to ensure they wouldn’t come loose. The good news is we won’t have to worry about welding in a sensor port when it does come time to install the gauges
Now it’s time to install the new dump pipe. Apply a dab of anti-seize compound to the studs before inserting the gasket and fitting up the dump pipe. It’s worth tensioning these nuts up to spec (check your workshop manual), because if they’re done up too tight you might snap the stud, too loose and you may develop an exhaust leak.
It’s also worth noting is that with the Domin8r exhaust system, the dump pipe is one piece down to the flex pipe which includes two mandrel bends to help with exhaust flow. There’s also no flange halfway down, just a flexible exhaust tube which helps smooth out the vibrations from the engine. Not only is it easier to install, but it’s also less restrictive
Now that you’ve got the dump pipe bolted up, you can install the first muffler and attach the rubber exhaust hangers at the next flange. It’s a good idea to lubricate the hanger again to help them slide over the chassis mounts with minimal fuss. At this point, only do the flange up finger tight because we’ll need to align the whole system before finally tightening each flange
Bolting the rear muffler section back up is essentially the same as when you removed it. Use the jack or stand again to support the exhaust while bolting the flanges together. Be sure to put the gaskets in place before bolting it all together, and again, leave the nuts and bolts finger tight to allow for final adjustment
With all of the pieces now in place it’s time to align each section and make any final adjustments. Each section is held in place and supported by the rubber hangers, but it pays to check the clearances around the chassis, crossmembers, firewall and diff; because each flange is designed with a small amount of adjustment, and any clearance issues should be corrected as you tighten each section.
Working from the dump pipe back, tighten each flange and hanger ensuring there is adequate clearance around any surrounding components. This step is particularly important if you’ve got aftermarket accessories like long-range fuel tanks fitted. As the HiLux we were working on was standard underneath, no special adjustments were needed
Finally, once it’s all bolted up and you’ve double checked the bolts and flanges, it’s a good idea to do a quick leak test. While the engine is cold, start it up and let it idle, then get a mate to carefully hold a rag against the end of the exhaust pipe. Blocking off the exhaust tip creates backpressure in the exhaust and will expose any leaks. It’s worth doing the leak test and rechecking that all of the nuts and bolts are tight a few weeks after to ensure nothing has rattled loose