I'm going to be replacing my headers when I fit my new turbo. The question is what should I fit. The turbo in question is a AFP5-20G

I've spoken to Harvey and I was 99% set on getting his ported and up-pipe set up, that was until I read somebody with a 20G and GT Spec headers had the same spool as the VF35 and got over 390hp on a similar spec to what mine will be. Or do I go for the equal length headers?

I'm not to fussed about the burble, yea it sounds good but when you hear it every day, its the same as having an inline 4.

I'm looking for a fast road car which the wife can drive with the kids in the back.

So,

Harvet Ported Headers & Up-pipe - Like the spool and cost

Kakumei GT Spec Headers & Up-pipe - Like the thought & could afford

????? Equal Length Headers & Up-pipe - Like the sound but would struggle to afford

Help

 

GT spec or gruppe-S V2 headers for higher bhp
or ported oe ones for under 400 bhp

 

What about RCM, Lateral performace, Hayward & Scott or Zen Headers?

 

I was amazed at the difference when I fitted a set of Harvey's (Not been mapped yet)...



...and I think they look cool, however your turbo setup is different to mine

 

I would say save your money and try the ported ones. They are very good.
I bought my GT Spec II replica headers from Tracktive and had them ceramic coated. These were slightly unequal length and so retain some of the burble, but when you 'blat' it, boy does it sing! lol.

 

Thanks for the feedback guys,



P1 FEK

What about them?

D-an-W

What differance did you notice after fitting your Harvey header? Did you get his matched up-pipe also?

MaDaSS

Have you tried ported headers before fitting your GT Spec Headers, or do you think the GT Specs aren't as good as you expected?

Thanks for any help,

 

Yes Nick replaced the up pipe with one of Harvey's at the same time (Adding a resistor to EGT Sensor connector)...



I can best describe it as "It feels more aggressive, definitely has faster spool and the car just wants to be off now" if that makes sense to you

 

hi, how much did it cost to have your headers ceramic coated?

 

I was going to change to GT Spec 2 Headers but after weighing up the costs involved in 1 buying the headers and 2 getting them ceramic coated i decided to get the OEM ones ported along with the downpipe.

Made a nic difference although it's difficult to judge the whole difference as i had a APS CAI fitted and mapped at the same time.

Zak @ Mocom Racing has got graphs to prove that the GT Spec headers do give an improvement over Porting the OEM ones but the cost didn't make the smallish performance increase seem worthwhile IMO

 

I was quoted just over £300

 

Ive got Gt spec II with up pipe on mine and its fab, at 4k plus the sound is amazing totally different to stock.

 

No i never did try the ported headers Nick. I had a serious case of "had money, will spend!" LOL.
The headers will be tested more when i get my latest mods fitted, but they are (imho) very good quality ones with the 3 bolt up pipe and all that.
They should come into their own once i swap all me bits and get Bobs mitts on my ECU.
TBH, its all down to cost Nick. Headers, good quality ones, are expensive, and when i had it done, the ceramic coating alone was over 200 quid (might even be more!). Cannot remember the exact amount, but if you look on either TSL or Tracktive website, they give you the total cost and looking at them they look the same or very similar headers for sale too.
Again, it depends on your final goal for power, torque, etc.
For my car and performance goal it was overkill with hindsight. Like a 900 quid hindsight! LOL.

Tracktive Solutions - Exhaust

TSL MOTORSPORT | Subaru Saab Mitsubishi | parts | repair | servicing | performance tuning | UK

 

I would say (since looking on the webby) its was more £300 ish. I said above £200 but that was wrong, since i have just looked on the Tracktive webby.

 

We haven't tried the Harvey ported versions, although what he says makes sense. We tend to go for the RCM headers when the spec demands, as they don't crack and blow like others we've seen. It would take a back to back test to sort that one out!

 

I've been offered a set of equal length headers which I'm pretty sure i'm going to have. Just really asking if anybody has any back to back experience of standard headers and equal length headers.

Thanks,

 

What make are the equal length ones you've been offered??

You'll loose the famous Scooby Burble with equal length ones. Wht not try Porting the OEM ones first and see what you think

 

I would personally recommend a set of Harveys headers and up pipe, i fitted a set of these to my UK MY99 and without a remap it felt a lot more responsive and gave me more power at the top end in the rev range to play with, they did make a significant difference. Top speed for my car went from an indicated 154 to off the clock (160) and revving to 6.5k in top gear (std wheels) this was the difference from fitting Harvey headers
From what i have heard, unless you are looking for BIG power then you don't loose much at all by having ported headers but you will gain at the lower end of the rev range, which will be the better option for a road car that needs to emphasize on driveability.
I now have a V4 Sti and will be happy to run a set of Harveys headers on this car at a proposed 400bhp ish level.

 

I have aset of gtspec/zen/rcm/etc headers ready to go on next year. and they look very well made, not like some of the cheap ones i have seen. so hopefully they will last.

 

I'm not sure which make the equal length headers are but I've never seen replica for far eastern equal length headers for sale, on ebay or anywhere so I'm guess they will be branded and they are at a good price.

I have thought long and hard about ported headers and Harveys are the best on the market from what I've read, maybe improving spool sooner and faster but I've never heard of a comparison with equal length. Ported headers and GT Spec headers seem to compare the same apart from GT Spec flow better high up making more power, but having said that it all depends on how its mapped.

I've read people running a similar spec to me with ported headers get around the 360-380hp, people with GT Spec headers are getting 370-400hp and from what I've read, similar spool to there previous standard VF35.

Advantages

Ported headers - Good Spool
GT Spec - Make Good Power
Equal Length - ???

Dis-advantages
Ported Headers - Maybe Restrictive
GT Spec - Stightly Slower Spool over ported
Equal Length - ???

Anybody fill in or correct my thoughts on the above?

 

I will let you know more about spool and stuff when i get my remap done as soon as i get a hold of Bob to do it! LOL.
I have the VF34 on mine.

 

Probably one of the nicest and reasonably priced sets of equal lengths I have seen recently are Tomei. Got a set for a friends Spec C twin scroll direct from Japan...very nice and comes with wrap, ties etc. They do 'em for TS and singles. May cost a bit more landed in UK tho.

 

My turbo back system is tomei and i was looking at gt spec headers by them but I've neer seen equal length headers that they make for single scroll.

 

Anyone know if Harveys still on here? Wanted to get a price for porting my headers

 

I've got these as well. Very well made, IMO. The flanges feel really solid and flat!

I didn't think they made any difference to the sound when I fitted them, but I changed the whole exhaust at the same time to a quiet one. Still sounds like a subaru

 

He certainly is although more often on the SIDC or TyneTeesScoobies websites.

Best bet is to email him direct with the year and model of your car and he'll email back with a cost breakdown.

harveysmith1 at btinternet.com

I had a set of his ported & wrapped headers & up-pipe fitted last month and the engine is now soo smoooooth. I would also recommend Darren (Harvey's tame mechamic) for fitting if you're anywhere close to Darlington.

Mark

 

Yeah you may be right, haven't actually seen the single scroll ones only the twin and that was all that was shown on the site. Very nice build quality tho' for the price, delivered to the door in Oz they were around $1000 AU (450 GBP?).

 

I went for Gt Spec II from flat4.
Quality is excellent. Sound awesome when on full boost and make the power.

 

I recently spoke to Harvey as I have one of his TD05-06 20G turbos and whilst in conversation i mentioned this thread.
He is a very busy man, Subaru's are only his hobby and not a commercial investment and as such rarely has the opportunity to get on SIDC or Tyne Tees but plenty folk on these sites know him, mostly due to his now infamous ported headers and FMIC's
He won't post on anything to do with his ported headers or Hybrid tube and fin front mount intercoolers if it gives the impression that he is pushing his own gear, he isn't a dealer, he has no commercial interest his ported headers and intercoolers only came about through his hobby so his only interest is serving the Subaru community with accurate assessments on products that he himself know to work through his own testing.
He has been involved in porting work for over thirty years on everything from two stroke lawnmowers , motorbikes, Jags to heavy diesels and Lycomming aero engines.
He felt it would be unfair to compare any set of ported headers against his own (without proper testing) and assume the results would be the same, as he has spent a fair bit of time on a flow bench testing to perfect the porting technique on the Subaru's and develop an efficient uppipe.

He would however, be happy to do back to back tests on his ported headers against GT Spec (or any other for that instance) and said that as far as he was concerned, the area under the graph would be the deciding factor and he was confident of the result up to 450 bhp. He had various examples of the early spool from his headers and his own Silver WRX Wagon does 422 bhp on one of his own turbos and ported headers but there are other examples with his headers well over 400 bhp.
If anyone wants to provide the GT Spec headers and uppipe and agree to a fair, honest back to back testing method, Harvey is happy to be contacted direct on harveysmith1@btopenworld.com.

I actually believe this would serve an excellent test to the Subaru community in general as it would answer several questions posed on a regular basis, there are plenty of options out there with regards to headers for the Scoob and i for one would be interested in finding out the definitive answer for the "what is best" question

For up to 450bhp (read as - anywhere from std to 450) which is where a vast majority of us with scoobs reside this would be an important factor, i do not like wasting my hard earned money and as such would like to know whether the mods i plan are worth my time and effort.

I applaud Harvey for offering to do this for us all, if anyone wishes to assist Harvey in the testing of headers and then happily publish on this forum the results then it truly would be fantastic and IMO their own reputations are likely to be enhanced no end

Over to you experts

 

I'd be more than happy to help in the testing and publish the results but logistics would have to be sorted.

I have an MY05 2.0ltr STi running an MD321T with GTSPEC GenII headers at circa 400bhp, I'd be quite happy to fit a set of ported headers to this car and run the test back to back on the same day.

Would suggest completing 2 runs; 1st run with the same map at 1.5bar optimised for the ported headers and the 2nd with an optimized map again at 1.5bar for the GTSPEC headers.

 

I would also suggest using Ecuteks DeltaDash road dyno to quantify the results, many 'experts' use it as it is repeatable and would illustrate real world running rather than a dyno where there may be too many variables.

I also have the perfect flat stretch of test track where all my testing takes place.