Whats the limit for the stock turbo as the top turbo in a twins kit, horsepower wise?

Im really itching to pull the trigger on twins but I cant decide to go w/ the;
stock/HT3B
stock/S400
HT2B/HT3B
Im thinking the HT2B/HT3B or the stock/HT3B just b/c I can get either for cheaper than I can the stock/s400, but I dont know later done the road Ill want to upgrade and the HT3B will hold me back? HELP

 

I know I'm one of the highest HP stock/S400 guys, I'm around 725HP at the wheels(11.93 with traction problems at 116, 6700lbs). Egt's are high at the track, but theirs hardly any smoke. http://www.youtube.com/watch?v=QnWI9iw2zgw you can also look at some of the others on their. I really like the stock/s400 nathan wright at MPI is the man. His kit looks good, and runs even better.

 

What are you wastegating the secondary at?

Just leave it up to the ECM-controlled solenoid on the HE351?

 

No the MPI kit uses a spring for the waste gate, the solenoid is out of the mix. I dont know what the spring opens up at though.