General LSX Automobile Discussion - Installed Magnaflow high flow cats lost power

Is it possibloe that I need to get the car retune after installing the magnaflow high flow cats I lost huge power I use to floor it a 20kmh and just couldn't keep it straight it spun through 1st and second now it just hooks and go.

My butt dyno is telling me that I lost 1/2 of what I gained. I was just wondering if anyone has experienced the same thing. My car doesn't smell like gas no raspiness at all from the exhaust but major power lost....It feels like I lost 1/2 of what I gained and I had a 50rwhp gain:mad:

Is it the can't have your cake and eat it 2 syndrom here would cats because of back pressure make the car run richer hence loose power .I will call my tuner and get it back on the dyno to check kit It does drive like I have just a cat back great on the ears :-)

You added a restriction to your exhaust system, hence you will lose a bit of power. A "high flow" cat doesn't mean it will ever flow as well as a straight pipe.

Having said that, you should never lose 25rwhp (half of what you said you gained) just by adding high flow cats to a cam + bolt-ons car, although it's possibile that the combo of adding the restriction of the cats plus whatever effect it may have had on your previous custom tune might have resulted in a noticeable net power loss over the ORY.

If you just want to reduce rasp, I'd use bullet muffers in the Y-pipe rather than cats. Only purpose for cats would be if you need them to pass emissions.

i can using a little power but not enough to notice. i gained a little power after i had my high flows gutted and im far from stock and that included a retune.

Is it possibloe that I need to get the car retune after installing the magnaflow high flow cats I lost huge power I use to floor it a 20kmh and just couldn't keep it straight it spun through 1st and second now it just hooks and go.

My butt dyno is telling me that I lost 1/2 of what I gained. I was just wondering if anyone has experienced the same thing. My car doesn't smell like gas no raspiness at all from the exhaust but major power lost....It feels like I lost 1/2 of what I gained and I had a 50rwhp gain:mad:

Is it the can't have your cake and eat it 2 syndrom here would cats because of back pressure make the car run richer hence loose power .I will call my tuner and get it back on the dyno to check kit It does drive like I have just a cat back great on the ears :-)

You may benefit from putting a cutout somewhere before those cats!!;)

You added a restriction to your exhaust system, hence you will lose a bit of power. A "high flow" cat doesn't mean it will ever flow as well as a straight pipe.

Having said that, you should never lose 25rwhp (half of what you said you gained) just by adding high flow cats to a cam + bolt-ons car, although it's possibile that the combo of adding the restriction of the cats plus whatever effect it may have had on your previous custom tune might have resulted in a noticeable net power loss over the ORY.

If you just want to reduce rasp, I'd use bullet muffers in the Y-pipe rather than cats. Only purpose for cats would be if you need them to pass emissions.

The sound level reduced by 50% as well so obviously restriction for sure I will slap it back on the dyno and that will tell me what it really did and maybe lookk at my tune again

Yeah, if I ever had an exhaust on my cars that were not straight true dual pipes (with mufflers) I would always have a cut-out. Best of both!

Yeah, if I ever had an exhaust on my cars that were not straight true dual pipes (with mufflers) I would always have a cut-out. Best of both!

Yeah that might be in the cards for later on I have to remove my Kook headers they hit bad on the frame on the drivers side I did cut a bit but it just is too far in on the motor mount plate same side and the top of the frame the passenger side. I really regret buying these I should of saved my money buy Pacesetters at least those dont hit 2 of my buddies just put them on with no issues. My exhaust guy just cant heat up anymore,he's scared the stainless will crumble!!!!

I am tired .... headers valve noise amazing when you modifie what you have to go through I hope the finish product is worth all the effort

Sell em and get the pacesetters lol

I have installed mangaflow hi flows 3" with duals and bullets dumped, I cant tell a difference in sound or power anywhere.

I have installed mangaflow hi flows 3" with duals and bullets dumped, I cant tell a difference in sound or power anywhere.

This is amazing to me, that you could perceive it this way. I've taken cats on and off (both stock and aftermarket high flows) of various setups, and the difference in sound is always striking....I mean there is NO question for me that the tone and volume has changed significantly.