Just as it is stated in the title. I have a 2004 6mt G35 with a vortech SC. I replaced the factory pulley to a 3.12 pulley a have a custom tune. I am thinking about removing my factory cats and replacing with a Hi Flow Cat. Do I need to retune the car, or I can get away with the old tune. Thanx

 

do you have a wideband A/F meter installed in the car?

 

i would get it re tuned because thats just me ... i like to know i am getting as much power as i can. But freeing up the exhaust more you are going to maybe lose a little psi which will chng your tune.

If you already have a tune your shop should re tune it cheap due to not taking more than a hour to re tune.

 

I am getting the afr wideband installed tomorrow, I was thinking to kill 2 birds with one stone.

The guy who tuned the car is about an hour away from me and he'll probably charge me the full price to retune it. I am guessing it is not even worth it to do all that work for a few ponies.

 

your going to free up the motor quit a bit....get it re-tuned

 

what ems? if UTEC, takes only a second to do a few logs and adjust the AF accordingly (assuming you have a wideband AF meter and logging software to combine everything)

your timing shouldnt have to be changed.

 

I am running the Split second box

 

A dyno with A/F and decide on whether a tune will be necessary...$75?

 

i recently removed my aps 2.5" test pipes and installed my 2.25" high flow cat's. did not retune, monitored my AFR's through out the power band and everthing looks ok. ( 11.0 to 11.5 AFR's ) did not alter timing, it is running like a champ! also picked up a bit of low end tourqe and lost minimal high rpm power. it is more enjoyable to drive now. a little more tourqe and no exhaust rasp....

 

Which HFC's are you using...I just switched to Crawford HFC's and I'm getting some rasp when boosting...trying to find an HFC which won't rasp with a Vortech....

 

so how did this end up turning out? how different was the A/F after the TPs?

 

+1

 

I am still on stock cats..