Spray is for the weak...unless your spraying Methanol

For a XP'ed, L36 build with no IC, or Meth...headers, and a good tune with other babbles and bolt-ons...I'd say a 3.4". GTP's come with a HD Transmission anyways...if your looking to upgrade transmissions...go to Triple Edge Performance. Best transmissions ever for the 3800 platform IMO. Horsepower...300-320 on the 3.4" to the crank I'd say...