Getting the hot gas out fast on my Mk5 GTI!

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I have been enjoying the KO4 Golf GTI. There was one thing I was noticing that was bothering me. It seemed that when the car started the boost the exhaust sounded that it was struggling to get the gas out. I started reading up on the net and there were a lot of mixed emotions about running bigger exhaust pipes. A lot of people said that going bigger on the exhaust will cause you to lose torque because of less back pressure.

On turbo cars, you don’t lose power or torque if you have a bigger exhaust. In fact the bigger the exhaust the better it is for your turbo. I am not saying fit a 4″ (100mm) exhaust on a turbo car that boosts 0.5 bar. That would just be stupid. It all depends on what you want to do with the car. Running a stage 2+ or stage 3 tune on a Golf 5 GTI it would be a good investment to run a 3″ (76mm) Exhaust system. The aftermarket downpipes are already 76mm so continue the size to the back.

The turbo itself already greats the back pressure the engine needs for its tuning effect with the exhaust pulses. The turbo just needs to be able to get the exhaust gas out the back as quickly as possible. Having back pressure behind the turbo will just reduce spool time. In fact, the turbo will have to work so much harder to try and achieve the preset boost values. This will cause the turbo to run even hotter, this will heat up the intake side of the turbo even more. All this means less power.

What exhaust exit to use?

The standard golf 5 GTI exit does not look bad with the twin pipes exiting the back.

I must say that VW designed a great looking car when they designed the MK5 Golf GTI. When I saw the MK5 R32 Golf I was amazed by the back end of the car. VW did a great front end of the Mk5 GTI and a great back end of the Mk5 R32. So I decided maybe it would be great to fit the Mk5 R32. Fitting twin 4″ (100mm) tailpipes at the back will compliment a 3″ (76mm) exhaust system really well.

What bumper to get.

I searched around and found that there was an aftermarket R32 exhaust replacement bumper. The only issue was no one had stock of the bumper at this stage.

I just could wait until someone brings in a bumper set and ended up going to the agents. Surprisingly the parts I needed weren’t as expensive as I thought it was going to be. Not as cheap as the aftermarket bumper but not bad. One thing that was nice I would not have to worry about fitment issues as the OEM parts will just fit. I sent the bumper in for spray painting just giving the painters the paint code of the car.

It was a few days later and I went to pick up the bumper from the painters. The bumper looked great. I was getting really excited to see the car with the new bumper. That same evening I stripped the rear bumper off and fitted the new bumper. I only left off the black skirting as I could fit that with the standard exhaust. The car started to look great.

Getting the exhaust done

I drove through to one of the performance exhaust shops that I always used. They stripped off the standard exhaust and I fitted the black trimming on the back. I had to leave the car with them for a day as this was a big job for them. Because of the size of the exhaust tube, they have to build the pipe with mandrill bends. This means the pipes are pre-bent and they have to cut and weld sections of pipe to make up the exhaust. The standard benders van bend the 76mm pipe without distorting the pipe.

They fitted 2 2 box system on the car, one round box(resonator) in the tunnel of the car and then one silencer on the side where the standard first box sits on the Golf 5 GTI. There were no boxes fitted on the back, that is where the 76mm pipe split into two 63mm pipes before exiting in the 2 of 100 mm tailpipes.

Collecting the Golf from the exhaust shop.

I went to collect the Golf from the exhaust shop, and I was amazed. The car looked totally different from that back, so aggressive. Now the Golf had an aggressive look from the front and the back. This was great.

Golf 5 GTI with the R32 bumper and 76mm Exhaust fitted.

Now it got to the start part. I started the car and it sounded completely different from before. It sounded a lot deeper and if you give it light revs you hear the popping of the exhaust. The Golf sounded great. Now for the test drive. This is what this was all about not the sound but to get the car to perform better.

The first time I put my foot down I was blown away, the bottom end feels similar to the standard exhaust but when I hit 5000 rpm it was like a valve opened up or something. The car put me down in the seat properly. This was insane, the car has never pulled this hard ever. This was money well spent. The car was load must not noisy load. It had a great tone and the exhaust just complimented the car brilliantly.

Recommendation

I would recommend anyone with a modified golf 5 or 6 GTI to go this route, it is worth it. If you run a high tune or plan to do so, put this in your budget.