I have heard that grooved friction plates give poor shift quality, I ordered a set of borg warner smooth high performance frictions but recieved waffled plates instead. they are listed as high perfomance plates on their site http://www.bwauto.com/aftermar/hiperfus.htm But most people prefer smooth plates. This trans is going behind a 427 big block, would these clutch plates hold up ok?

Buy the book on rebuilding a TH400.

The waffled plate eases the clutch application. You simply remove the waffled plate and install a flat plate making sure the total clearance is still within limits.

I have a stack of disks from a bunch of trannies. There are 2 main sizes. Mix and match the plates to get the proper spacing.

As for the friction disks, just about any brand will work fine.

Stephen, I have read the th400 book also, the waffled plates I am refering to are the frictions. Not the waved steel plate. I think most manufacturers make frictions in several different configurations, such as radial grooving, parrallel grooving and waffled to name a few. The pictures are on page 218 in the book.
Seems like everyone has their own preference.

back in the early days, the only HP frictions you could get for the T400 was the green waffle cut frictions.

These frictions were along the same design as the Allison frictions. The grooves let the oil get out during the application of the pack. Smooth frictions apply a bit smoother as the oil escapes.

Friction design and material used has changed by leaps and bounds in the last 10 years.

Back in the mid 1980's I used common brown smooth frictions in a T400 that I was putting 900 hp from a blown big block into. THe tranny never showed any signs of distress on the frictions.

I run a narrowed 9 inch Ford with 13x31 slicks on the car, so the power was getting hooked up.

My question being...... are you worried about holding power or comfort shifts?

If you are going to use the Borg Warner Hi-Energy frictions, use the smooth in 2nd & 3rd gear applications. In forward, use the standard flat BW's with no groove for a small diameter TC and BW's with grooves for the large diameter TC's. DO NOT take out the waved steels in 2nd & put in a couple of waved steels in 3rd. Leave the in between rubber seal in 3rd gear, take off the 2nd sealing ring on the center support instead, use the late solid teflon rings instead of the cast iron rings on the front pumpp & center support. If you want long life with performance shifts, always use the Trans-Go Performance Shift kit & hook up the modulator (even in full manual applications)it keeps the front pump alive. GM has now an extra wide 2nd gear band which is using the Hi-Energy material (works very well in TH400's). This is some of the things that I would recommend for TH400, if you want more information on this please call me. One last thing DO NOT block accumulators, restrict them.....YES, block them.....NO! A properly setup TH400 can handle 800 to 900 or more horsepower & LIVE!

The wide band for the T400 you speak of , is this the 4L80E band?

They require a longer servo apply pin I believe.

Yes it is the 4L80E band. If you do not get the pin to apply the way you want, you might need the longer pin.