450kw and BTR ET's

[3Katz]

A question for you guys who run or have run before they exploded BTRs at the track. My ute has recently been tuned to 450kw at the hubs and is only 1 second quicker than when I had 260kw. A quick run down:

Built engine

Plazzy cooler

Garrett GTX3582 gen2

Built BTR (stock stall speed convertor)

345 gears

ET Streets

PCMTEC tune with antilag

I can not beat 12.90, runs 12.90's all night. No matter my technique variation (handbrake/antilag activated/etc) I can't better that time. It seems to leave the line pretty hard then immediately bogs down until boost is back up then it's off and pulls hard once she's away and even the change into 3rd feels strong. No wheelspin, traction is not an issue. I'm doing 2.5 sec 60ft's and 112mph. I figure I need a higher stall convertor but I'm sure people run much faster than that with stock convertor. It's loads of fun and I'm looking forward to more practice and would really appreciate some tips, and thoughts as to what might be causing my 60ft times.