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2018 Q4 with Fiamenghi Ti exhaust, Race Mod, and Tecnico wheels.
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You guys do know that the tire manufacturer as well as the owners manual say that you need to substantially increase tire pressure before making a high speed run? IIRC you need about 40-42PSI cold in the 225 40R19 tires for speeds over 125MPH. Otherwise you risk a blow out from a sidewall failure, and a blow out would be disastrous at such speeds.

In spite of the safety rating of Giulia, the safety systems are not really designed to cope with such high speeds. Airbags are not fast enough to do anything useful, for example. I do not know if the safety belt retractors are fast enough, but I doubt it.

A long while back a forum member posted a QV run on the Autobahn. He managed to run it up to a bit over 290KPH (about 181MPH) before traffic forced a slow down.
 

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2018 Q4 with Fiamenghi Ti exhaust, Race Mod, and Tecnico wheels.
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Regarding the speedometer accuracy, at high speeds it is different and more complicated than at the speed limit. The forces on the tire at high speed make the tire diameter increase making the speedometer read lower than reality but other forces also make the tire slip on the pavement making the speedometer read higher than reality. I expect that at 150MPH on good pavement the tire expansion effect is dominant and may be enough to overcome the 2-3% bias that is built into the speedometer for legal reasons. OTOH, "the internet" indicates that the expansion effect is trivial. I dunno if I believe it; the expansion effect is clearly extreme for (much more flexible than your Giulia tires) dragster tires.

Here is some info from tire rack on inflation pressures and vehicle loading for driving at high speeds, with an example for one particular tire provided:

 

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2018 Q4 with Fiamenghi Ti exhaust, Race Mod, and Tecnico wheels.
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Yes, just needs some hood vents. My hood gets kinda shaky at high speeds. Did you notice the same?
I've seen my hood shake at 50MPH with a strong (50-60MPH) cross wind.
My question relative to hood vents is if the air flow would actually work to reduce front end uplift. I'm still kicking around the idea of fitting a QV CF hood to my Q4. Note that the QV CF hood may alter air flow around the radiator unless some kind of baffle is fitted.
 

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2018 Q4 with Fiamenghi Ti exhaust, Race Mod, and Tecnico wheels.
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This is a good candidate. Probably cheaper than OEM. Needs to be painted though:


If I ever have to replace the hood that's what I'll get. Otherwise, you can keep your eye on wrecked Giulias... unfortunately the hood rarely survives an accident intact.
The Feroce Carbon hood seems to be described as a CF veneer over FRP. It is probably heavier than the aluminum hood. Someone pointed out to me that if the vents were the only thing one is going after, paying a custom shop to cut some holes in the original aluminum hood and install vent screens would be much less expensive than buying and painting a QV CF hood. OTOH, I am not certain if the understructure of the aluminum hood is amenable to vent hole cutting.
 

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2018 Q4 with Fiamenghi Ti exhaust, Race Mod, and Tecnico wheels.
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Not that it comes up often, but I have the same issue with the sunroof on my 2019. Not sure what to do about it. If I tell the dealer my sunroof flutters at 125 mph, I'm pretty sure they'll tell me to GTF out of their store.
Yet another reason why sport models should not have sunroofs?
OTOH I think @DrEndAll was talking about some wind noise, not fluttering or other alarming sounds coming from the shatter prone glass that is posed to kill your rear seat passengers.
The car is supposed to be safe-enough up to the 149MPH speed limiter.

As I have stated before I have seen easily noticeable harmonic vibration on the rear edge of my aluminum hood at 50MPH driving speed in a strong cross wind.
I think the CF hood should be more resistant to such vibrations since CF is stiffer than Al and it is likely to be thicker as well. All of this makes me wonder if the 149MPH speed limiter value is due to instability of the aluminum hood at high speeds. I am also suspicious that there may be a front uplift issue at high speeds unless you have the hood vents.

Lastly, please note that the Giulia hood has 3-count-em-3 latches, one on each side plus the emergency latch in the middle.
 
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