Trouble holding my car on the brakes

Hi.

Busy tuning my Supra on the road, having difficulty with the Left foot braking.

The torque comes in hard around 3500rpm as both turbos come online, making it difficult to hold the car brakes, car just wants to accelarate.

I don't have access to a dyno, so need to figure out a way to complete the tune.

Any tips or recommendations on how to proceed?

Thanks.

Press harder on the brakes for more brake pressure. Now you may also need to try a higher gear (smaller overall ratio) to reduce the torque at the wheels.

Vehicle brakes are much more powerful than the engine (and if not, you need to fix that!)

Sometimes a good way to find a dyno is contact the dyno manufacturers and ask who their customers are in your area. You may be surprised who has a dyno and would be willing to rent you dyno time.

Thanks David.

I was using 1st/2nd, car was breaking into wheel spin.

Will try 3rd and check the results.

Brakes were recently overhauled, so should be fine in terms of operation.

There are a few dynos but none with operators I trust to handle my car. I do have one potential lead, hoping it pans out.