another backpressure question...
Thread Starter
TECH Enthusiast
Joined: Apr 2002
Posts: 533
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From: Canada
another backpressure question... ok heres my story.. my cars just rolled 16,000 miles and i bin taking my cats out since 10,000 miles every 2 years after inspection.. n e ways i have a borla cat back with everything else stock.. so i made up some cat bypass pipes.. work awsome.. but i do have a little rasp... so i decided closing off the straight thro borla and going thro the muffler would help. it did.. but sounded really back and way to quiet.. so i took that off last month and put a dynomax bullet in place of the borla.. sounds perfect now! without the cats it sounds loud and deep! n e ways im trying to sell the muffler and a guy calls today asking about it.. told him i got no cats and it was to quiet for me.. guy was suprised.. u shouldn't take out ur cats he says.. i say y not?! haha then he goes on about a mecanic told him that these motors need packpressure and that u could burn the pistons and vavles??? this has me really worried now! i did a search about packpressure and learned alot but still not clear about y u have to have it? arnt lots of u guys running ORY, headers and bullets?? thats higher flow then my stock manifolds,cat bypass stock crushed Y pipe and thro my bullet muffler at the back.. my car is pretty much new still.. and i don't feel like burning the motor up.. so is there a fix? one thread said that u just gota tune it.. richen the A/F mixture? and i beleave its the exhuast scavaging i gota be worried about not backpressure?? should i put my cats back in then?? its just so quiet tho.. plz help me here.. i don't wana drive my car till i no its safe to do so!! thanx alot guys!
do worry about it thats all crap. Thats just crap GM tells its mechanics to make them think that better not remove cats. do we listen? no because thats wrong. no tuning needed.
backpressure kills power about 700 degrees of the crank rotation and can help make some (which this is negated) with the other 20 degrees.....lol
Your engine will be fine without cats.....and exhaust can mak a difference in power, but involves exhaust scavenging/velocity a lot more than backpressure....
Your engine will be fine without cats.....and exhaust can mak a difference in power, but involves exhaust scavenging/velocity a lot more than backpressure....
Thread Starter
TECH Enthusiast
Joined: Apr 2002
Posts: 533
Likes: 0
From: Canada
ok good so im safe now then? ya i noticed alot of shops will get pretty made when u say u got no cats.. concidering its illegal to take them out.. the place i got my pipes bent for i worked at for a bit they just said we never touch the car 
so that was cool.. i also found some posts about the way removing the cats moves the power band up a bit? thats fine with me.. as long as thers a increase in power not decrease. thanx for the replys! 
so that was cool.. i also found some posts about the way removing the cats moves the power band up a bit? thats fine with me.. as long as thers a increase in power not decrease. thanx for the replys! 
