Is there a reason something like this isn't available to certificated aircraft.
If some aircraft are able to have aftermarket turbo systems installed, then why not can something like above be installed.
In general, money and market are the main reasons. Every defined FAA type certificated product (aircraft, engine, propeller) starts with an approved type design. In order for that product’s TC designation to remain valid and airworthy, each product must conform to its type design at all times unless properly altered via one of several regulatory paths.
In the case of your stroker kit that would usually be one of the following: the TC holder/OEM can provide a stroker kit via a FAA approved revised type design; an OEM/Vendor can develop an approved Supplemental Type Certificate (STC) and produce stroker kits for sale to the public; or, an aircraft owner can initiate their own approved alteration via Part 43.
While the FAA approval costs are usually the 1st detractor, how the market/risk plays into the decision to provide stroker kits usually is the main reason OEMs/Vendors do not venture out on these types of upgrades.
If non-TSO avionics can be installed in certificated aircraft,
In general, installing non-TSO avionics is on opposite ends of the aircraft modification spectrum than adding a “stroker kit” so there is really no comparison per se. But for reference, an owner has basically 2 options if they want to change something on their TC’d aircraft: a part replacement or aircraft alteration.
For a part replacement (remove part A and install a new part A or part B) the
replacement part must have an FAA approval (OEM part, PMA, TSO) in order for the aircraft to conform to its type design. There are exceptions for FAA defined Standard Parts, Commercial Parts, etc. but in general if that
replacement part is not approved the aircraft does not conform to its type design.
But… in the case of non-TSO or other non-FAA approved parts it can still be installed on a TC’d aircraft under a Part 43 major or minor alteration (remove part A and install a part 34f2; or, add a part 34f2). By definition, this alteration modifies the aircraft type design to include the non-TSO avionics via the APIA signature in the aircraft record. Thus it is the “properly altered” side of the equation.
how the IA reads the 14 CFR 91
FYI: Part 91 will offer no guidance to the APIA involving aircraft maintenance. Part 43 is where all this guidance starts.