Post #20 shiny T is pretty much what I would've choose, if I was to improve.
On the matter about heat, the fiber...cloth and aluminium, you have the aluminium warmed once and it will still "keep" the fiber underneath heated.
We all know the cooler the air intake, the better. And as mine is SC an intercooler is a must. On that note you seem to have no space for re-routing the air intake, but keeping it cooler as long as you can.
Have you seen this:
View attachment 623647
K-flex, Arma-flex ...who knows what brand you can find in HVAC store near by. The aluminium is reflective for the radiation but the "rubber" is low conductive (can not say if less than the fiber you mentioned) and the "closed cell" structure is a very good insulation (general thing, right).
But it is about 1cm thick, that means space!?! You know better, how much you have, but fiber...cloth plus "rubber" and aluminium reflector... would've been better. Imagine 2 layers of insulation before the house of yours is exposed to heat cold weather outside...plus 1 reflective coating on the outside for the radiation...
And about the Airflow that Turbo mentioned along with thermodynamics we have dynamics of fluids and friction.
The different flow (change of direction) has specific resistance, that means friction, the friction is a heat source (put your both hands together press and slide, is this how you warming up your hands when cold) imagine high speed air flow that has layers, more friction? Why layers?
Well, water was mentioned as fluid and river bed has "slow" motion/speed near the shore and higher flow/current speed/motion in the middle, imagine 2 river beds on top of eachother (mirrored) - there is your air intake, lower air flow on the ends (pipe wall itself) then friction and higher flow in the middle! And one brutal (general term - contrasting speech) out of shape T piece to "force" both air flows clashing first and then going the right way.
Pardon my inaccurate explanation (far from engineering language) just I started 4 am UK time to BHX Airport, to get delayed flight, time on the airport, lack of info... finally started with nice delay, landed at the destination and currently have 2 more hours (out of 6-7 hours - total of 500km bus ride) with nothing but a coffee in the morning...the headache is...the bus stop was to a place that was having only WC working and outside coffee machine...