does removing the catalytic converter add HP? Options

[nate95]

Hey i was just wondering if i were to remove the catalytic converter if it would add any horse power? or what about getting a "Y" pipe before the cat. so i can still have the cat. but have it go straight out when i want to race?

[j0e_p3t]

ok
first...

most US Celicas have 2 cats (primary and secondary)- 94-95 STs have 2, 96-97 STs have one - the secondary, 94-99 GTs (94-95 cali) have 2, the 94-95 fed (non-cali) have just one, the primary.

removing one or both of your cats will not "add" hp but will "free up" hp from your engine. Removing the secondary cat won't do much but removing the primary cat will give your engine a better (less restrive) air flow - removing both will be less restrictive obviously. How much you ask ? a free flowing exhaust will free up about 5-8 at maximum. That doesn't seem like much but these are economy engines, not performance engines, we are talking about here...

removing these will increse and decrease a few things

increase
flow freeing up some hp with better responce throughout the RPM band
the amount of harmful emissions emitted

decrease
gas mileage

the

so if i do my exhaust... i should remove my primary and keep my secondary? would my car still be legal if i keep at least one of my cats on there?

This post has been edited by j0e_p3t: Apr 9, 2006 - 3:39 PM

[Batman722]

so if i do my exhaust... i should remove my primary and keep my secondary? would my car still be legal if i keep at least one of my cats on there?

since you live in Cali the emission tests are pretty tough out there so removing your primary would probably make you fail. You might pass if you remove your secondary cat, but I don't know.

IMO If you get an exhaust done, get your car inspected right before, so your sticker would be good for a year and when it is ready to get inspected again, put your old system back on. Then just swap again after.