does spec v need back pressure?

[SpecvSpeed03]

im hearing rumors that engine failure on the spec v's can be caused by 2 things, pre cat failure and guts getting sucked back into engine, and running exhaust with cat deletes having no back pressure ruining piston rings?

does anyone know of this? and is it true?

[consultIII]

the cat issue is indeed true; most the the problems were related to the 2.5l. The vvt sucking back the detiorated cat material that scores the cylinder wall. the 2007 and onwards have redesigned cats and have solved that problem.

Haven't heard about the cat delete/ backpressure problems at all. Are you taking about removing the precat, installing a header and leaving the rear cat? Can't see that causing issues.

[SpecvSpeed03]

well yea, i have obx header and down pipe, both cat deletes .. relocated the o2 sensor and then it went down hill .. like i said, a guy told me im the 4th person he knows that after deleting cats on spec v, the cars went down hill .. just wondering, if we are suppose to have back pressure on these motors or not? and if so, would a catback exhaust provide enough back pressure?

this my first import car ive done .. so i really have no idea