Audi A4 1.8TFSI Tuning: The Space Station Gets a New Exhaust System

“Is it rocket science? Well for a newbie yes, it may seem like it. And con men will reassure you that it is and that you need to spend 8 thousand Malaysian Ringgit too.”

The quote above came from my pal, Zairul Nizar, who was the owner of the fine Audi A4 1.8TFSI that I reviewed in a previous post. This was the Audi that had engine mount problems and was the Audi choked full of sensors and electronic gizmos. And this isn't the top of the line, full monty R8 or an RS4. Anyway, the local distributor decided to hand him a quote of over $800 for a pair of engine mounts.

Now as the car was just out of warranty and being a sensible chap, Zairul went to an Audi specialist garage instead to get a second opinion. Three weeks later the waiting paid of and the specialist had managed to source a pair for something around $300. Imagine the vast difference of pricing between an official source and a specialist garage. It definitely pays to get a second opinion AND also start ignoring anything that has links with the authorized distributor or importer. Zairul had basically saved a ton of money for himself. So as a reward for himself, he decided to spend some more money on the car on something that really mattered to a petrolhead. He decided that it was time to start tweaking it a little.

The car is an A4 1.8TFSI from 2008/9 (the B8 series). It came equipped with S-Line specs where the seats are trimmed in leather and in cloth unlike the full leather trimming of the usual ones. It also came with good looking 5 spoke 18inch rims and shod with some pretty grippy Michelin Pilot Sport tires. The A4 is pretty good looking; low and swoopy looking for a sedan. The only change that the owner, Zairul, made to the exterior of the car was the addition of the Caractere rear diffuser/valance and a boot spoiler. This addition looks good and blends in well with the original lines of the car.

The A4 1.8TFSI has a 1.8liter 160bhp and 250Nm turbocharged engine that utilizes a Continuously Variable Transmission (CVT) with 8 programmed shift points to transmit power to the front wheels. It feels punchy and because of the CVT (which does not feel very yo-yo like or CVT like), the A4 seemed to be in the correct gear during a kickdown or when you downshift manually with the flappy paddles located behind the steering wheel.

We have found out that the 160ps, 250Nm, 1.8liter direct injection and turbocharged engine was more than adequate to take on most 2.0liter to 2.5liter cars out there on the market right now. Even on a damp road the ESP will blink like crazy if you're wringing the A4 in those conditions. I think the official specs are a little under-rated as I think it makes more than the quoted 160ps. This engine is a gem in some ways. But my pal basically thought that it needed a slight boost in power and it is in Car Throttle that I have chosen to report the upgrades of this Malaysian Audi A4 1.8 TFSI.

Yup. It has taken me this long to actually start explaining the point of this article. This is something like a James Bond movie or an episode of Alias where the introduction takes a good fifteen minutes or so.

The car's only engine upgrade was a K&N drop-in air filter before this. This addition somehow made the engine breathe a little better and improved throttle response of the A4 too. So now as the car's warranty period has ended it was time to start with some slightly more exciting measures. Like junking the stock exhaust mufflers.

The A4 1.8TFSI comes with 2.5inch diameter piping running through a catalytic converter located at the engine bay (close to the turbo). After this it runs through a middle box muffler and a rear box muffler. These two items are about the same size and weigh between 4 to 5kg and we knew if we junked these two items we'd lose at least 2 to 3kgs as well as gain some power as the stock mufflers are baffled and do not release exhaust gasses quicker than one with a straight through type. Check out the size and odd shape of the rear muffler below.

It isn't rocket science actually. More air in, more air out. We lose the restrictions in overall exhaust gas flow, we gain power. This is especially true in a turbocharged car as less restriction is always a very good thing. It makes the turbo spin faster because of it. So what we did at the garage was find a 2.5inch middle muffler and a rear muffler of the same diameter to replace the stock mufflers. We also chose those that basically were the same diameter as the piping (2.5inches), with a straight through design (no baffles or S-bends and where you can basically see through the other end) and without any louvers or raised dimples, just a perforated tube – as anything blocking the flow of the exhaust gasses actually add more backpressure, which does not help the engine make its optimum power. Remember, an exhaust system basically frees up whatever horsepower that your engine is already making. That is actually the job for headers, which help in the whole combustion process.

We didn't choose to spend money on one of those branded ones from those famous Audi tuners as we've actually seen a few mufflers from supposed top European tuners and they are actually shoddy looking (wavy stainless steel casing, insubstantial welds, dull shine) compared to what we can get off the shelf here in Malaysia. For example, the muffler from a tuner that costs close to $1,500 here in Malaysia looks cheaper than the US$100 rear muffler that we installed on the A4 (which was coupled with a custom made twin exit pipe that actually was well made as the chap welding and cutting it took his time fabricating it). These off the shelf mufflers are actually as good or better than the tuner items. 

Of course, brand snobs will tell you otherwise, that the items have been thoroughly tested and have gone through rigorous testing. But again I say, it isn't rocket science. Get the principles correct and you can't go wrong.

So after a couple of hours and some welding later, the A4 has an exhaust system that is about 4 to 5kg lighter (allowing for a slight improvement in the car's power to weight ratio), and new big bore tailpipes (allowing for better looks). There could be an actual power increase, but that would only be substantiated with a dyno run so I am not reporting any actual or factual power gains till then. But after Zairul had taken the car for a short drive right after the installation, the benefits that were immediately felt after the installation was the the car felt a little more eager. It was like it had gained bigger lungs as the power started to come in slightly earlier and the top end pulled better; and with an even crisper throttle response.

The new setup makes the A4 sound slightly meaner. It now has a nice bassy burble, somewhat like how a Mk6 Golf GTI sounds. “It is loud enough to make me feel that the car is sporty, but it is quiet enough so that my kids can sleep during those longer drives” quotes Zairul. And the rear of this A4 looks and sounds a helluva lot better too. Maybe this is what's important most of the time.

No warning lights came on after this installation. So what we've shown you in here is that it is possible to still tune a car that has sensors everywhere. Maybe it is because the A4 does not have sensors located on the mufflers and none on the air filter box. This simple fact would allow owners of the A4 to indulge in some basic tuning mods in what I consider as a space station instead of a car. That folks, it the purpose of this long winded article.

Now that the car has the most basic mods in place, the next step is an ECU reflash. There are a few different ones on the market right now. As an example, an APR stage 1 will bump the power up to 215bhp and around 330Nm (245lbs/ft). Now with the air filter and the freer flowing exhaust system, it should get better gains. So the question is what reflash and when?

Whatever it is, I will report the next round of upgrades made to this red A4 here at Car Throttle.