Need advice (warnings) re: intended mods on my 996

[argonaut]

...O.K., my 996 C4 ('99 model, 57k miles) currently has the Porsche sports suspension & Porsche sports exhaust. Full Porsche service history, and approx 6 months left to run on a Porsche used car warranty.

I'm SERIOUSLY considering a tuning package from G-force Motorsport. This would be sports headers/filter & ECU remap, plus sports cats. Total cost, including fitting would be approx £4k. Chris Davies at G-Force assures me that they can reliably extract another 40 bhp at least (accessible from mid-range, not only high revs), and with improved mid-range torque.

All things considered, should I go for it? I think I need someone to talk me out of it as I don't have money to burn, but like the idea of my 996 with close to 350 bhp!

[domster]

That seems like a good power output for those mods, if it can be acheived, and the price is reasonable for 40 bhp more. Remember the X-pack on a 996 turbo costs something horrendous like 10k and only gives another 34bhp - with an easily tuned Turbo engine.

The 996 is also an expensive car, and 4k of mods seems more reasonable than on a 2k 924.

If it is a noticeable improvement to performance or driveability, go for it. But as Mel pointed out quite rightly, even half that on driver training (Jim Clark week long racing course used to cost £2500) will probably get you from A-B quicker and more safely than another 40bhp.

Cheers
Dom

[ninemeister]

We fit the Cargraphic package onto the 996, which consists of headers, 100 cell cats, silencers, K&N panel filter and revised DME, parts costs around £2700 + VAT, fitting is £300 and it gives a 30bhp improvement. If you also fit a larger throttle body and a set of cams you can see nearer 40bhp but it adds £2000 to the bill. I have no torque figures for the 3.6, but on the 3.4 it gives 370 & 382Nm respectively. So I'm not sure how G-Force find the extra 10bhp but I suppose as long as you have proof (before & after dyno results) you won't mind paying the extra £1000 or so.

[iguana]

The figures G Force claim for engine mods always seems rather high to me. They do back it up with the print out from the dyno runs, however you can make that print out say what ever you want due to correction factors etc. I do feel if you went directly from G Force to another rolling road the figures achived would be lower. Im not slagging off the company as they have a very good reputation, but I just feel some of their rolling road figures are a bit optimistic!

[ultra violent]

If anything I would say their dyno under reads. Lee's 996tt puy down 310 at the wheels which seems low to me. However it ties out with other cars I know that have been on their dyno (mine included).

[ninemeister]

......which all points out the futility of comparing chassis dynos with each other. No two anywhere will give the same figures, so you must always use dynos as a comparator only.

The bottom line is that if G-spot test your car before and after, on the same road, in the same gear, with the same tyre pressures, and the power figures both at the wheels and at the flywheel are up by the same percentage, then the conversion does what it says on the tin.

However, more fundamentally, if you don't trust your supplier and have to independently test the car somewhere else before and after, then either come clean and agree to a no-win-no-fee job beforehand or find yourself another supplier. Personally speaking, I would rather not have a customer at all if he/she did not trust us to do the job right.