work on my existing intake manifolds to make them flow smoother.
He says he would charge me approx. $900 usd all inclusive.

I suppose he would work on the intake manifolds similar to the way he
would gas flow a cylinder head?

This seems like a good deal, but what do you guys think? Will the polishing
and the end result be very different from this "EXTRUDE and HONED"
finish from Dinan?
Would love some feedback from you guys.

Thanks in advance!

Jeff Wong

I suppose you didn't want to or have time to do such a job? Maybe the Ferrari brothers might be able to help you. I suppose the end result is worth it only if there is bad matching of intake/exhaust to manifold. Just hope he doesn't booger up anything.

Jeff,

I would put the $900 into the exhaust system to improve its flow before trying to get more air through the existing set-up. There is more room for improvement in the exhasut system than in the intake system.

my .02

where would I start to improve the flow?
The Cats would be one and I can't think of what other things?
Pipework?
Thanks.

Jeff

The cats, the resonator, and probably the most important the mufflers. The OEM mufflers have relatively small diameter inlets.

Thanks Simeon,

With the aftermarket mufflers done I only have the Cats and resonators to sort out.
Thanks again.

Jeff Wong

I will poke my head in here and say that this sort of thing might cause you to need to retune your ECU, which might be a tad bit more than the simple intake job.
Randy --- Words from the unwise.

I agree, Randy. This could lead to a "dominoe effect" of tuning that might be a bit more than you want to take on, Jeff...

I agree, Randy. This could lead to a "dominoe effect" of tuning that might be a bit more than you want to take on, Jeff...
Jack, but then again maybe he has the need for speed? British version of Simeon perhaps?

Thanks to all, I think I may have to check things out before diving into this mod.

Jeff Wong

I agree, Randy. This could lead to a "dominoe effect" of tuning that might be a bit more than you want to take on, Jeff...

Based on his mods to-date, I think Jeff's immune from the dominoe effect...!!

I bought a set of intake manifolds with the intention of possibly modifying them and installing them on my 750iL. I knew the only way that I'd ever get around to it was to do it on a spare set, rather than taking my car out of service.

What I found is that the walls of the intake tubes are fairly thin. There is simply not enough metal in them to significantly increase the port diameters. I don’t claim to be an expert, but from where I stand, it would appear that any gains to be had would be from polishing the inside surface and possibly matching the ports to the heads. I’d have to agree with Simeon and others that the gains from intake modification may be minimal.

Thanks Dave!
Do you think by increasing the exhaust pipe diameter between the CATS and the Muffler will be beneficial? Will it mess up the back pressure?

Can you reccommend any good high flow cats for our 750's?

Thanks in advance.
Jeff Wong

I was actually impressed that the exhaust system, including pipes, seems to be well designed with fairly large pipes for a stock vehicle. I'm not certain, but I think that the pipes may be slightly larger than on a 740.

Jeff,

You didn't ask, but let me suggest that the next mod you should make is to moderately lower your car. I know this is on your wish list, but it will give you more ROI than just about any other (for the price).

If you have never driven a car with a modified suspension, you will love the change in driving precision it offers.

The best analogy I can make, for you skiers out there, is that a properly tuned suspension is like skiing on a high-end slalom ski. The car just responds that much more quickly to the driver's inputs...

Just a thought.

Cheers!
I will bear these things in mind.
It like having the Strong Strut in that I can corner safer and faster than previously without one on. Suppose its all to tune the car for better performance.

Jeff Wong

Cheers!
I will bear these things in mind.
It like having the Strong Strut in that I can corner safer and faster than previously without one on. Suppose its all to tune the car for better performance.

Jeff Wong

If you like the strut bar, you'll love a new suspension...

The Dinan Manifolds apparently release around 40 BHP from memory(with ABSOLUTELY NO OTHER MODIFICATIONS required),so I would beg to differ that modifiing the exhaust first would be a good route to much more power,although I may be wrong.My feeling is that the intake side is the more restrictive-I believe demonstrated by the very noticable difference the K+N filters made to my car.I too came across someone here in the UK that was willing to port and polish a pair of manifolds-but I am interested to hear that they are not very thick walled.I wonder how the 850csi/Dinan/Alpina etc compare to the standard 750 items :redspot