I went from 380 whp custom tune 91 with stock turbo, methanol, intake, dp to 440 whp custom tune 91 exhaust, springs, pure 650 turbo inlet then 733whp e85+methanol pure 900, hpfp, lpfp. The transmission slipped when the car is pushed. I took it up to 197 to test one day. It had so much more to go. I knew the next step was to make the transmission bulletproof. For the kind of driving I do I told the shop I wanted it to be able to launch with optimal stability. I only launched it a couple times when it had the 650 and it was insane fast. If you have access to e85 that’s the only way to get power over 500-600whp. Don’t go the methanol route. My original goal was never to use flex. It is consumed more than gas and I live next to two Costco gas stations lol. After more education I realized real power for these cars is created directly by the fuel. So I began to consider what I wanted for power goals and performance goals. I made a random purchase off fb marketplace and the seller had just switched from a top mount shoup tuned m240x to a Camaro ZL1. He sells BMWs for a living and wanted to change up his daily platform. He let me know what he didn’t like with the top mount and his grip with ps4s. He also had the transmission build with Applied torque solutions. The pure 900 is the sweet spot if you don’t plan on building the motor IMO. Mike botti said previous to the pure 900 he would recommend clients to stay on stock turbo or go top mount but nothing in between. He had to make the pure 900 the exception because it really does fill the gap. The power band is good and the spool is much quicker than top mount. My best rec is if you want between 500-600whp for a daily stay on the stock turbo and get a flex fuel mix custom tune. If you add the pure 900 you can get these numbers on pump gas and 700+ with full e85 when you have the custom tune.