I e-mailed Toyota NA about the spring perches here is what they sent me, names redacted:
"Dear Mr. --------,
Thank you for contacting Toyota Motor Sales, U.S.A., Inc.
We appreciate your inquiry on the TRD Bilstein® on the 2015 4Runner TRD Pro and regret that we are unable to answer your inquiry. Based on the information we have available, the 4Runners are shipped from the factory with both sides even.
Each Toyota dealer has, on site, a customer relations manager to oversee the various operations and address any inquiries or concerns a customer may have. Therefore, we would like to refer you to the Customer Relations Manager at your Toyota dealer regarding your inquiry on the TRD Bilstein®.
If you would like us to contact your dealer on your behalf and have a member of the dealer’s management team follow up with you directly, please provide us with the name of your Toyota dealer and your telephone number by replying to this email. Once contacted the dealer's management will contact you in two business days, and will report back to Toyota once the follow-up is completed so we have a record of both your experience and the outcome.
If we can be of further assistance, please feel free to contact us.
Sincerely,
---------
Toyota Customer Experience"
Doesn't really answer the question since we know the Bilsteins are installed at port.