Do you sell brake master cylinder stoppers for other cars? We only sell the products listed on our website. If it's not listed on here, then we don't sell it. We don't do any custom work. Sorry. I'm running a bigger brake master, will this still fit? Yes, the brake master cylinder stopper will fit providing that you're still running the standard brake booster. Does the firewall really flex that much? Yep, it sure does. It's actually very noticeable under hard braking conditions. The brake master cylinder stopper truly does make a difference and is one of the good value for money mods.