Japanese: These can be used as well, but you have to do some research with a trusted vendor. The reason for this is you have to ensure that you have the right Japanese manifold for your vehicle due to JDM/USDM differences in injector type and throttle body type. Using these is fine, but you cannot use the TGV CEL fix #1 as detailed above with them as they have no rods to do this with.
If I gut my TGVs myself, how should I fill up the hole where the rods were? You can either have it welded up (probably the preferred method) or many have successfully used various bolts or epoxies to fill them up with great success.
If I gut my TGVs myself, should the inner surface be polished or have a slight texture? The easiest way is to use a light abrasive to smooth over your rough porting work to leave a slight textured finish. While the smooth vs. rough debate has and will wage for years to come with internet fluid dynamics specialists, it probably matters not but to say it’s 100% easier just to leave a smooth, but textured finish.
What about external coatings for TGV Deletes? While thermal dispersants would be most beneficial, the benefits would be very hard to measure. But, for some this would be considered the “best” option. Most are happy enough to color match them with spray paint to their car’s color scheme or leave them unpainted. To paint them, simply clean them very well, tape off the top and bottom mating surfaces, and use a quality high temp spray paint.
How will leaving the rods in affect me vs fully ported options? The rods are actually quite large in diameter for what they do. You can grind them down in profile so that when they are in their open position they block less flow. Leaving them in untouched is an option as well. They do present a blockage in total flow, but it’s impossible to say whether they would present a loss in HP on the dyno vs. the no bar options. In the perfect world, you’d remove them totally and fix the associated CEL through engine management or the APG TGV delete motor “cheater blocks” vs. leaving the rods in.
What about phenolic gaskets? These are plastic based gaskets that limit the thermal conductivity between the hot engine block and the TGV/Intake Manifold. As with external TGV thermal dispersant coatings, phenolic gaskets are the best to use, but their benefits are nigh impossible to measure on a dyno. Most users just consider these a “must have” and get them with little thought though. Some use OEM gaskets, some OEM and phenolic, some have reused OEM and/or phenolic gaskets unlike some Subaru junctions, the TGV/motor junction isn’t particularly prone to leaking. This isn’t carte blanche to re-use gaskets akimbo, but re-using gaskets here isn’t a deal breaker like it can be in say the pre-turbo side of the house.