Hello Magna Maniacs,

I'm thinking of upgrading my ride's intake with a Streetfighter II manifold followed by a hi-flowing cat (maybe a Magnaflow 200 cpsi). What I'd like to find out from you experienced experts are:

1) Are the gains worth the expenses?
2) Would it improve my somewhat lazt mid-range grunt?
3) How much performance are we talking about for each item based on my current setup?

The mods on my TJ II Sports so far are:

- 'flowed' throttle body (RPW)
- K&N panel filter
- Fuel pressure regulator (RPW)
- Pacemaker extractors (Mettams)
- Walker sports muffler

I like the low end responsiveness and the way it pulls from around 2500 at the moment.

cheers fellers!

Ok,
Now this will turn into a large debate however as far as my experience goes with these streetfighter manifolds, use it to hold down something heavy as this is all they are good for

The ones I have seen and the one I hvae here, the casting internally is shameful, the ports do not even come close to matching up and the way it hangs off the lower manifold is just a disaster in the waiting

There is a member here, Jasonsvrx who has gained a lot of power from his car using a std manifold with no need to use this streetfighter crap. In addition to this, I have shown this manifold to several race engine builders who do a lot of very high performance work, the comments they have made about the rubbish design, the poor casting and the general manifold would not really be suitable to be put on these forums

The thing you need to look at is what your end goal is, and then you need to start saving and be prepared, like anyone serious about building a car that does thrill, to spend a reasonable amount of money on the car. YOu can not get gains with no budget, not real gains anyway

The list you have so far, the fuel pressure reg should not be needed unless you are doing serious mods, K&N, well a paper filter will get you about 2kw more than a K&N if you have a clean paper filter, Throttle body, these are not really flowed as such they just remove a small lip which has not been proven to take any power away at all.

You have also removed one of the best suited mufflers for a Magna and used the Walker, most likely sounds great but will not really gain anything lol

If you really want to get some gain, send the ECU off to SKR and get a postal tune, this will even up the range. Then if you really want to make some gains, throw a 380 donk in the car and you will never look back

From memory the prototype streetfighters were good, but then someone else took over and they wern't made quite right from then on?
There was a thread about it somewhere.

Righto, manifold advice taken. Any ideas about the 'hi-flow' cat converter?

Also, the SKR option sounds more like what I'm after. Any more details on that?

The 380 donk sounds the nuts and perhaps down the track that may be a consideration. For my reference, just how complex is the conversion?
I'm not a skilled mechanic by any standard so most of it would have to be done by a workshop - which will be a cost issue.

cheers.

If you wanted to stretch your budget (Which looks like around the $1400 mark at the moment) you may also be interested in putting in some better cams. I've been doing quite a bit of research lately and I hate to say it but RPW's billets are some of the cheapest around (Tighe are after $1200/set, RPW want $1000).

Upon installing cams, you will need to have the car tuned. You have 2 options here, you can either get an SKR "postal" tune (telling him which mods you have) but you will need to send your ECU off for a week or so, I believe the cost is around $350. The second option is to find a reputable Evo tuner with ECUFlash capability and providing them the latest Magna Tuning Kit found here <Edit GTVi: link censored pending copyright and rule review>

Personally this is what I am in the process of doing atm, mine will be tuned by Pulse Racing in Menei and they have quoted $600-650 for the tune which is around 4 hours on the dyno.

I was going to go for 272 camshafts in a 6G74, however after speaking to Camtech (reputable NSW cam grinder) I have decided it is a better idea to start with a 6G75 first so I am on the prowl for a 380 wreck, if you have room this is a great way to get a 6G75 as you can sell the rest of the parts to recoup the costs involved in getting your engine and put that towards supporting modifications.

I got a Magnaflow 200cpi Highflow cat installed after the stock one shat itself, didnt feel like it changed much, exhaust note did improve but.

Brilliant. SKR tune will be scheduled. As for the cams, I take it that it's meant for top end grunt?