most popular with our customers is the Active Autowerke. Spot on fitment, no CEL, great sound.
https://x-ph.com/active-autowerke-aa-bmw-supra-b58-catted-downpipe/
The best value for catless is the MAD B58. Spot on fitment, lifetime warranty...
I recommend the MAD brand, lifetime warranty, top-notch support, and no-hassle return. Also unbeatable price
https://mad-us.com/mad-b58-downpipe-w-bracket-bmw-f-g-chassis-supra/
nothing will void your warranty. A dealer can refuse to do a free repair if they think your mod caused the damage.
I don't see it happening with an air intake, which is why its one of the most popular mods
Sorry I forgot to post the link to the non BOV
https://store-gd6olw6.mybigcommerce.com/vargas-vtt-a90-91-supra-single-piece-silicone-charge-pipe-non-bov/
It says its compatible with HKS but the BOV is not offered as an option on their website. They must not have the BOV in stock yet...
Its still brand new, i have not had a chance to test it and compare power. I would not think there is going to be any power lost. Silicone is easier to install, performance and reliability should be the same as Aluminum
Link
Vargas VTT A90/91 Supra Single Piece Silicone Charge Pipe BOV Version...
Description
VTT is proud to offer the very best BOV charge pipe solution for the Toyota A90/91 Supra platforms. This system completely does away with the restrictive, and muli-connection stock charge pipe system, and replaces it with a single 6-ply, Heat Resistant, Wire reinforced silicone...