Question regarding LS1 headers and retune

[mike_is_bored316]

Hi i currently have a series II vx ss which has a twin 2 1/2 difilippo catback exhaust system (stock cats) a ramjet otr cold air intake and MAFless tune my question is regarding firstly if i would need a retune with new headers and cats to really make the most out of it and how much a retune would cost.

And also id really like to get difilippo headers and cats since i already have the difilli catback system but i see there are slight variations of 4 into 1 difilippo header i was wondering what are the differences in slightly different sizes: 1 and 3/4" 4 into 1 and 1 7/8" 4 into 1 or 2" 4 into 1

I should mention it is my daily driver and id like a deep throaty sound and the best performance obviously also i was told try y pacemakers are better for the street but struggle up top and that difilippo 4 into 1's are only if you want to future proof the car incase of an agressive cam upgrade. Ive done a search on this forum and have not been able to find an answer to all of my questions listed above i would greatly apreciate any advice of help on this subject, Also at the moment at last dyno my car currently has 210rwkw (auto) how much would i expect high flow cats and headers to improve this figure.
Cheers

[RavenLS1]

yes you'll need a touch up tune, should only have to pay for dyno time if you go back to the same place you got your original tune from, you'll prob gain about 10- 15 rwkw.

[mike_is_bored316]

thanx for the info mate i would be going back to gm motorsport in melton for the retune im just worried about the price and unsure about difilippo 4 into 1's which they recommend which would be great for a cam upgrade ect but for me pacemaker try y's it seems like are a better option and slightly cheaper as i dont plan to ever put a cam in it.

[RavenLS1]

ive got difilipo 4- 1's and when it was bolt on only made 240rwkw, i'd litsen to gm as they no there stuff.

[SIG-054]

Just get some 4 into 1's, you wont lose anything with them. How much are the difillipo headers? any reason for not going with pacemaker etc?

[Not_An_Abba_Fan]

If you decide on Pacemaker, I can do you a good price on them.

4-1's will give you a beefier sound than tri Y's, there is no real difference in measurable power between most extractors, just where the usable torque is in the revs. Tri Y's tend to keep the torque lower in the rev range, while 4 -1's move it up higher.

[davleigh]

just on this topic, if i were to upgrade my system to a vz clubby system, would i need to re do my tune? i just got the otr and mafless done the other day.
atm i only have stock everything on my car apart from a 2.25in cat back. (aparently it was spose to be 2.5 but took it to an exhaust shop and found out otherwise)

thanks

[Sabbath']

Any change should also be accompanied by a tune change.