Need advice on header and overpipe
 

So far i have Invidia n1 exhaust with a invidia catless front pipe with OFT i would like to know what overpipe is best for gains and wont give me that raspy sound and also do you know how much whp i can get out of a tomei uel header?

There is little to be had gain-wise from overpipe, i'm not sure that it changes a lot to sound too (unless rubbing :)). Main sound changes come from catback, main performance gains come from catless header+tune. If you want to change overpipe just-because of sake of exhaust mod completeness, i'd probably get whichever is cheapest without reported quality issues.

Ace header FTW
JDL ultra quiet front pipe FTW

Header:
Ace or nameless header (best)
Tomei or JDL (budget friendly and good)

Op:
JDL or tomei

A budget friendly package would be MXP, comes with the header and OP.

Gruppe-s UEL header is the same as Tomei, but at a better price (made in same factory by same folks). Don't bother changing OP.

Hmm, why are you guys suggesting different headers? OP asked info on overpipe and estimated power gains for specific Tomei UEL header he has already chosen. Even more so that he mentioned OFT, which might limit gains from headers like Ace's/Nameless', longtube EL headers that greatily benefit from good Ecutek tune to get most out of them, not so much from generic EL OTS tunes.

I don't think the overpipe directly contributes to rasp, nor radically improves power output - that said, my favorite overpipe is made by Motiv simply because of its build quality. Invidia makes a mid-priced overpipe that looks pretty well made and if you use it and choose not to replace your header, then all of your exhaust components match (if that kind of thing matters to you).

If you decide to get the Tomei catless header, you'll see pretty substantial horsepower gains with an OFT tune, but you'll need to replace your Invidia catless front pipe with a catted one (I know nothing about California emissions, so even then you may not have a prayer at passing emissions). I can't report on the raspiness of that combination, but the Invidia N1 with any open header is going to be very loud - so loud, I think you'll need to look at a quieter exhaust to keep it bearable. The Invidia Q300 is probably a good option for you at that point.

Keep in mind that these are completely different to the choices I made for my car, but I offered these suggestions based on the specific questions you asked and the components you already own.

I agree with @RJasonKlein

ANY catless header will make your current exhaust setup extremely loud. the N1 is already loud by itself being a catback, but if you add a catless header along with an overpipe and front pipe (removing the cats), it will be obnoxiously loud. but at the end, it is up to what you like. if you don't mind loud exhausts or extreme rasp, then you won't have a problem with the setup

mate if you already have an N1 and a catless front pipe and you add catless header the first thing you will want is a set of ear plug or muffs. It just going to be off the planet loud.

The overpipe may net you 1 or 2 hp on an NA car. It wont effect sound.

If you want to go to a catless header , then tis will generally net you about 10 wheel hp. But its going to be increadably loud with your current setup.

Either put your stock catback on or get a quierter catback than N1, like Q300.

even putting in a resonated or high flow cat front pipe wont quieten down an N1 catback coupled with a catless header.

maybe read the Basic Bolt on Mods Guide (coloured link below)

thanks everybody for the advice im most likely buying the tomei uel and selling the catless front pipe for a high flow. buts thats in the future right now im trying to see i get a turbo kit. thanks again!

The Gruppe-S UEL is feasibly identical to the tomei, and made in the same factory...but cheaper, and you can even get their overpipe as a package deal for like $75 extra. I absolutely love mine, haven't had a single problem. Gruppe-S is a vendor on here and you order directly through them, which removes the middleman and keeps the price down. But what Steve said, if you run a catless header and an N1, you're gonna have a bad time.

@bryansuriel3: if you will install turbo kit, why do you need header, that most probably will not work with turbo (unlike with SC)? Maybe worth saving that money for something else?