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Originally Posted by joshbrz
I wish I knew a bit more about how the tuning aspect worked  this is what my tuner said!! |
https://www.hksusa.com/application/f...59012-00en.pdf
HKS says the boost actuator is set at 89kPa, which is 12.9psi, but there is some overboost that gets the car above that, as seen in their graph of the catless setup, which is your setup. So like DarkPira7e said, you are seeing raised boost levels because of the decrease in backpressure and subsequent better flow leading to a gain in boost. According to the catless graph, the car might be seeing around a peak of 95kPa, which is around 13.77psi. As you can see from the second graph, the modification of the rod reduces the boost initially by semi-cracking the wastegate and bleeding exhaust, but the turbo still wants to pop the wastegate fully at spring pressure, so that is why boost slowly raises to within around 5kPa or 0.7psi of its potential, which is around 90kPa or spring pressure.
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Loosening the nut up to maximum 3mm to decrease the initial boost pressure
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In short, the mod the tuner did reduced psi for much of the RPM band, but your catless frontpipe added that boost back to the top end, as if you were running a stock frontpipe without the mod. Your best bet would be to run the stock front pipe with the mod, but you will still be getting to a peak of 85kPa or 12.3psi according to the graph.
I don't know why they call it a 90kPa (13psi) vs 75kPa (10.8psi) peak setup, when the results clearly show that the mod with cat still gets the car to 85kPa (12.3psi).
If you want less boost, while keeping the frontpipe, or if you want less boost even with the stock frontpipe and mod, then your only option is to replace the internal wastegate with a replacement that has a 8psi spring or something. Discuss this with your tuner.
https://www.rallysportdirect.com/par...tor-7psi-black