According to everything I have learned about these cars, 3.4 with no headers or at least pems = boom. Instead of a 3" downpipe, get some SSAC headers that will include the downpipe. That might be the reason you lost your last engine.
Yea i though i saw pem on there so used to seeing it with the dp
Definatly need headers or pem/dp for the 3.4
98 gtp sedan forest green ,S1X intense cam,Intense pcm,Magnaflow exhaust, ubend delete,TEP trans 3.29's,3.4 smoothflow mps,Dyno'd 281hp and 371ft #'s of trq at the wheels http://www.cardomain.com/ride/3338681